Summer is Coming! Join the Game of Timers Competition to Win Epic Prizes. Registration is Open. Game starts Mon July 1st.

 It is currently 18 Jul 2019, 10:32

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# To develop more accurate population forecasts, demographers

Author Message
TAGS:

### Hide Tags

Intern
Joined: 26 Feb 2016
Posts: 21
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

20 Mar 2016, 04:55
TommyWallach wrote:
Hey All,

I got asked about this privately, but I think the same question was asked by mymisc as well. The question is, do we need the "would" here, and why? The issue is that this sentence is a hypothetical/conditional:

To develop more accurate population forecasts

We could reword this as "If we wanted more accurate forecasts, demographers..."

In a conditional construction, we need the "would". Look at how it would work in a NON-conditional:

To develop accurate population forecasts, demographers have to know a great deal more...

See how, in that example, without the "more," we're just talking about a fact (how forecasts are developed accurately)? But with the conditional, we need the complete conditional construction, with "would."

Let me know if you have any follow-up questions!

-t

GmatDestroyer2013 wrote:
yolandaxu wrote:
How can we find out that the sentence explains a hypothetical situation? Are there any signal words?

To identify the hypothetical situation you have to understand the meaning also there is ,in some cases, inclusion of 'if'/'wish' clause that marks the hypothetical situation.
Think is the sentence is talking about an uncertainty (contrary to reality) for example :

If it rains,(then) we will go out -- here IF denotes the conditional occurrence of an event in future on which another event depends which might occur.
Here we used 'will' because the conditional clause is in present tense.

other cases Past and Perfect - uses would and would have respectively.... Other point to note such sentence always uses plural verb form (instead of was -- it will be were) irrespective of the subject
If I were king, I would rule the world.
If I had two cars, I would have never own a bicycle.

"would" is generally used for the refer future in the past.

Is there any clear guideline (eg. "more" as a must-be signal word) in distinguishing between a factual sentence and a hypothetical/conditional situation?
Seriously, I fail to justify why this sentence can't be a factual statement (since it lacks "if"), which makes "would" redundant.
Intern
Joined: 26 Feb 2016
Posts: 21
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

25 Mar 2016, 00:56
Post bump. Still unable to understand this even with extensive reading online. Any taker?

gmatretest wrote:
TommyWallach wrote:
Hey All,

I got asked about this privately, but I think the same question was asked by mymisc as well. The question is, do we need the "would" here, and why? The issue is that this sentence is a hypothetical/conditional:

To develop more accurate population forecasts

We could reword this as "If we wanted more accurate forecasts, demographers..."

In a conditional construction, we need the "would". Look at how it would work in a NON-conditional:

To develop accurate population forecasts, demographers have to know a great deal more...

See how, in that example, without the "more," we're just talking about a fact (how forecasts are developed accurately)? But with the conditional, we need the complete conditional construction, with "would."

Let me know if you have any follow-up questions!

-t

GmatDestroyer2013 wrote:
yolandaxu wrote:
How can we find out that the sentence explains a hypothetical situation? Are there any signal words?

To identify the hypothetical situation you have to understand the meaning also there is ,in some cases, inclusion of 'if'/'wish' clause that marks the hypothetical situation.
Think is the sentence is talking about an uncertainty (contrary to reality) for example :

If it rains,(then) we will go out -- here IF denotes the conditional occurrence of an event in future on which another event depends which might occur.
Here we used 'will' because the conditional clause is in present tense.

other cases Past and Perfect - uses would and would have respectively.... Other point to note such sentence always uses plural verb form (instead of was -- it will be were) irrespective of the subject
If I were king, I would rule the world.
If I had two cars, I would have never own a bicycle.

"would" is generally used for the refer future in the past.

Is there any clear guideline (eg. "more" as a must-be signal word) in distinguishing between a factual sentence and a hypothetical/conditional situation?
Seriously, I fail to justify why this sentence can't be a factual statement (since it lacks "if"), which makes "would" redundant.
Retired Moderator
Joined: 14 Dec 2013
Posts: 2870
Location: Germany
Schools: German MBA
GMAT 1: 780 Q50 V47
WE: Corporate Finance (Pharmaceuticals and Biotech)
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

28 Mar 2016, 05:37
6
1
gmatretest wrote:
Post bump. Still unable to understand this even with extensive reading online. Any taker?

gmatretest wrote:

Is there any clear guideline (eg. "more" as a must-be signal word) in distinguishing between a factual sentence and a hypothetical/conditional situation?
Seriously, I fail to justify why this sentence can't be a factual statement (since it lacks "if"), which makes "would" redundant.

A more accurate population forecast does not exist now. A forecast exists, but it is just as accurate as it is now - it is not more accurate than it is now. Developing a more accurate forecast is a hypothetical situation - it may or may not be possible to develop more accurate forecasts. The outcome depends on another hypothetical situation: the demographers would have to know more. It may or may not be possible for the demographers to know more. Hence the statement is hypothetical and not factual.

However if we already knew that it is possible for the demographers to have more accurate knowledge and in such case more accurate forecasts could be developed, we would not then require "would" - in that case the statement would be factual and grammatically correct without "would". However we do not have a grammatically correct option without "would" ( A wrong - comparison issues , B wrong - use of economical). Hence option D is the best.
Retired Moderator
Joined: 22 Jun 2014
Posts: 1102
Location: India
Concentration: General Management, Technology
GMAT 1: 540 Q45 V20
GPA: 2.49
WE: Information Technology (Computer Software)
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

06 May 2016, 09:07
english_august wrote:
To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

A. have to know a great deal more than now about the social and economic
B. have to know a great deal more than they do now about the social and economical
C. would have to know a great deal more than they do now about the social and economical
D. would have to know a great deal more than they do now about the social and economic
E. would have to know a great deal more than now about the social and economical
_________________
Senior Manager
Joined: 24 Jun 2016
Posts: 340
GMAT 1: 770 Q60 V60
GPA: 4
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

25 Jun 2016, 10:58
The phrase has to use a tense that isn't the present. The comparison has to follow a parallel structure. The impact is economic rather than economical.

All 3 conditions point to one answer choice: D.
_________________
Stuck in the 600's and want to score 700+ on the GMAT?
If this describes you, we should talk. I specialize in getting motivated students into the 700's.

\$75/hour as of July 2019. I am not accepting any more students for the Fall 2019 application cycle, but if you are planning to apply in 2020, feel free to reach out!

HanoiGMATTutor@gmail.com
SVP
Joined: 06 Nov 2014
Posts: 1877
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

Updated on: 21 Jul 2016, 21:53
english_august wrote:
To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

A. have to know a great deal more than now about the social and economic
B. have to know a great deal more than they do now about the social and economical
C. would have to know a great deal more than they do now about the social and economical
D. would have to know a great deal more than they do now about the social and economic
E. would have to know a great deal more than now about the social and economical

Since we are talking about future, there is an uncertainty. hence we need to use would not have.
Eliminate options A and B

There is a big difference between economical (cheap) and economic (related to money matters)
We are talking about economic determinants.
Eliminate options C and E

Correct Option: D

Originally posted by OptimusPrepJanielle on 20 Jul 2016, 21:25.
Last edited by OptimusPrepJanielle on 21 Jul 2016, 21:53, edited 1 time in total.
Director
Joined: 04 Jun 2016
Posts: 562
GMAT 1: 750 Q49 V43
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

21 Jul 2016, 00:37
english_august wrote:
To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

A. have to know a great deal more than now about the social and economic
B. have to know a great deal more than they do now about the social and economical
C. would have to know a great deal more than they do now about the social and economical
D. would have to know a great deal more than they do now about the social and economic
E. would have to know a great deal more than now about the social and economical

First of all one should know use of ECONOMICAL is incorrect in this sentence. "ECONOMICAL" means affordable, cheap, not expensive
The correct term to use here would be "ECONOMIC". ECONOMIC means related to money, economics or monetary reasons

Option B,C and E are out because of wrong word "ECONOMICAL"

Option A and D remaining

Since the sentence suggest a future action, "would" is the correct tense

Option A is out because it makes a faulty comparison and is not parallel. Also does not have the correct future tense "would"

Option D is flawless.:- Correct term "Economic" Correct comparison "demographers .... great deal more than they do" and correct future tense "would"

A. have to know a great deal more than now about the social and economic
B. have to know a great deal more than they do now about the social and economical
C. would have to know a great deal more than they do now about the social and economical
D. would have to know a great deal more than they do now about the social and economic
E. would have to know a great deal more than now about the social and economical
_________________
Posting an answer without an explanation is "GOD COMPLEX". The world doesn't need any more gods. Please explain you answers properly.
FINAL GOODBYE :- 17th SEPTEMBER 2016. .. 16 March 2017 - I am back but for all purposes please consider me semi-retired.
Intern
Joined: 17 Nov 2015
Posts: 6
Location: India
Concentration: Entrepreneurship, General Management
Schools: ISB '17
GMAT 1: 750 Q40 V35
GPA: 3.73
WE: Business Development (Energy and Utilities)
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

15 Sep 2016, 01:36
[quote="devinawilliam83"]To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

A. have to know a great deal more than now about the social and economic
The sentence refers to an action in future tense. "would have" correctly reflects the tense than "have"
B. have to know a great deal more than they do now about the social and economical
The sentence refers to an action in future tense. "would have" correctly reflects the tense than "have"
"economical" refers to something good value in return,while "economic" is something related to money
C. would have to know a great deal more than they do now about the social and economical
"economical" refers to something good value in return,while "economic" is something related to money
D. would have to know a great deal more than they do now about the social and economic
Correct: tense of the sentence is correct. Word "economic" is correctly used
E. would have to know a great deal more than now about the social and economical
"economical" refers to something good value in return,while "economic" is something related to money
click "kudos" if it helped
Senior Manager
Joined: 17 Sep 2016
Posts: 252
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

18 Feb 2017, 04:03
Hi mikemcgarry,
How are you ?

I know here is a video to explain of this question on Magoosh, unfortunately, YOUTUBE is not available in China, I am afraid I need your further writing explanation.

My version, from O 16 # 61, is a little different with the initial poster, I found that last word of choice is economic , instead of economical

OG 16 # 61 version,
To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.
(A) have to know a great deal more than now about the social and economic
(B) have to know a great deal more than they do now about the social and economical
(C) would have to know a great deal more than they do now about the social and economical
(D) would have to know a great deal more than they do now about the social and economic
(E) would have to know a great deal more than now about the social and economic

I am struggling with A, D and E.
I can understand that comparison should be logical, meaning
for this case, the comparison is either future time VS present time, or future knowledge VS present knowledge,

Here is my reasoning , please point out my faults. thanks
A) have to know a great deal more than now about the social and economic
first, I think "have to know "is sensible, because it presents the necessary to get the knowledge in order to improve future accuracy.
second, I review choice A as omit, -- have to know a great deal more than( they know ) now.
"they" refers to demographers, know is a verb that appears preceding.

D) would have to know a great deal more than they do now about the social and economic
E) would have to know a great deal more than now about the social and economic
first, IMO, "would have to know" presents demographers' necessary in the future, I think of it as available as well.
second, both D and E have a comparison that "demographers have to know " VS "they know/do" .. I am not sure how should I distinguish D and E, because I think that E omits "they do".

have a nice day
>_~
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4487
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

20 Feb 2017, 11:27
zoezhuyan wrote:
Hi mikemcgarry,
How are you ?

I know here is a video to explain of this question on Magoosh, unfortunately, YOUTUBE is not available in China, I am afraid I need your further writing explanation.

My version, from O 16 # 61, is a little different with the initial poster, I found that last word of choice is economic , instead of economical.

OG 16 # 61 version,
To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.
(A) have to know a great deal more than now about the social and economic
(B) have to know a great deal more than they do now about the social and economical
(C) would have to know a great deal more than they do now about the social and economical
(D) would have to know a great deal more than they do now about the social and economic
(E) would have to know a great deal more than now about the social and economic

I am struggling with A, D and E.
I can understand that comparison should be logical, meaning
for this case, the comparison is either future time VS present time, or future knowledge VS present knowledge,

Here is my reasoning , please point out my faults. thanks
A) have to know a great deal more than now about the social and economic
first, I think "have to know "is sensible, because it presents the necessary to get the knowledge in order to improve future accuracy.
second, I review choice A as omit, -- have to know a great deal more than( they know ) now.
"they" refers to demographers, know is a verb that appears preceding.

D) would have to know a great deal more than they do now about the social and economic
E) would have to know a great deal more than now about the social and economic
first, IMO, "would have to know" presents demographers' necessary in the future, I think of it as available as well.
second, both D and E have a comparison that "demographers have to know " VS "they know/do" .. I am not sure how should I distinguish D and E, because I think that E omits "they do".

have a nice day
>_~

Dear zoezhuyan,

How are you my friend? I'm happy to respond.

My friend, you are correct: other sources on the web list choice (E) as "economic," not "economical." I changed the original post.

What's wrong with (A) is subtle. The sentence begins:
To develop more accurate population forecasts . . .
The implication is that the forecast now are not accurate, at least not as accurate as they could be. This is suggesting a contrary-to-fact situation, the existence of something better than what exists now. In fact, the whole sentence has this contrary-to-fact tone, comparing what would be ideal to what is true now. All of this requires the verb "would have." This has a hypothetical implication. The verb "have" sounds too factual, as if all these ideal conditions were already in existence. This is why (A) is wrong.

To understand the difference between (D) and (E), think about a simpler example.
Version #1: In order to get a perfect score on the GMAT Verbal, you would need to know more than now.
Version #2: In order to get a perfect score on the GMAT Verbal, you would need to know more than you know now.
Version #1 sounds awkward. Yes, we know what the speaker is trying to say, but it sounds awkward. It sounds as if we are comparing knowledge to the location in time known as "now." It's awkward in a bizarre way. By contrast, version #2 is flawless.

Much in the same way, (E) is a a bit awkward, and (D) is clear and flawless. Thus, (D) is the better answer of these two and the best of the five.

Does all this make sense, my friend?
Mike
_________________
Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)
Manager
Joined: 05 Dec 2014
Posts: 198
Location: India
GMAT 1: 690 Q48 V36
GPA: 3.54
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

01 Dec 2017, 04:29
mikemcgarry wrote:
zoezhuyan wrote:
Hi mikemcgarry,
How are you ?

I know here is a video to explain of this question on Magoosh, unfortunately, YOUTUBE is not available in China, I am afraid I need your further writing explanation.

My version, from O 16 # 61, is a little different with the initial poster, I found that last word of choice is economic , instead of economical.

OG 16 # 61 version,
To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.
(A) have to know a great deal more than now about the social and economic
(B) have to know a great deal more than they do now about the social and economical
(C) would have to know a great deal more than they do now about the social and economical
(D) would have to know a great deal more than they do now about the social and economic
(E) would have to know a great deal more than now about the social and economic

I am struggling with A, D and E.
I can understand that comparison should be logical, meaning
for this case, the comparison is either future time VS present time, or future knowledge VS present knowledge,

Here is my reasoning , please point out my faults. thanks
A) have to know a great deal more than now about the social and economic
first, I think "have to know "is sensible, because it presents the necessary to get the knowledge in order to improve future accuracy.
second, I review choice A as omit, -- have to know a great deal more than( they know ) now.
"they" refers to demographers, know is a verb that appears preceding.

D) would have to know a great deal more than they do now about the social and economic
E) would have to know a great deal more than now about the social and economic
first, IMO, "would have to know" presents demographers' necessary in the future, I think of it as available as well.
second, both D and E have a comparison that "demographers have to know " VS "they know/do" .. I am not sure how should I distinguish D and E, because I think that E omits "they do".

have a nice day
>_~

Dear zoezhuyan,

How are you my friend? I'm happy to respond.

My friend, you are correct: other sources on the web list choice (E) as "economic," not "economical." I changed the original post.

What's wrong with (A) is subtle. The sentence begins:
To develop more accurate population forecasts . . .
The implication is that the forecast now are not accurate, at least not as accurate as they could be. This is suggesting a contrary-to-fact situation, the existence of something better than what exists now. In fact, the whole sentence has this contrary-to-fact tone, comparing what would be ideal to what is true now. All of this requires the verb "would have." This has a hypothetical implication. The verb "have" sounds too factual, as if all these ideal conditions were already in existence. This is why (A) is wrong.

To understand the difference between (D) and (E), think about a simpler example.
Version #1: In order to get a perfect score on the GMAT Verbal, you would need to know more than now.
Version #2: In order to get a perfect score on the GMAT Verbal, you would need to know more than you know now.
Version #1 sounds awkward. Yes, we know what the speaker is trying to say, but it sounds awkward. It sounds as if we are comparing knowledge to the location in time known as "now." It's awkward in a bizarre way. By contrast, version #2 is flawless.

Much in the same way, (E) is a a bit awkward, and (D) is clear and flawless. Thus, (D) is the better answer of these two and the best of the five.

Does all this make sense, my friend?
Mike

Hi Mike,
option d looks the best. But I have a query with the use of would. Would is used correctly when there is a reference of another past event.
Ex- If I had 10 million \$, I would buy the luxury car.
Ex- The scientist believes that the machine would be wonderful.

The above example is wrong as 'believes' is in present. If believes is replaced by 'believed' the ex becomes correct.
Again, if we the have the sentence- I would buy the car, this sentence is wrong as we dont have a clear past event reference.
Now, in option D, would have to know a great deal more than they do now about the social and economical- here do is in present tense and so how can we ignore the past tense reference.
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4487
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

04 Dec 2017, 17:47
sunny91 wrote:

Hi Mike,
option d looks the best. But I have a query with the use of would. Would is used correctly when there is a reference of another past event.
Ex- If I had 10 million \$, I would buy the luxury car.
Ex- The scientist believes that the machine would be wonderful.

The above example is wrong as 'believes' is in present. If believes is replaced by 'believed' the ex becomes correct.
Again, if we the have the sentence- I would buy the car, this sentence is wrong as we dont have a clear past event reference.
Now, in option D, would have to know a great deal more than they do now about the social and economical- here do is in present tense and so how can we ignore the past tense reference.

Dear sunny91,

I'm happy to respond.

My friend, many student labor under the misconception that one can arrive at GMAT SC mastery by memorizing some mythical "complete" set of grammar rules. This rule-based approach to the GMAT SC is doomed to failure. Yes, there are some important rules, and it's important to know those--for example, SVA. Nevertheless, many patterns in language are much more complex and demand broad intuition about the language. The only way a non-native speaker develops this intuition is through the habit of reading. See:
How to Improve Your GMAT Verbal Score

I would say that any rule you have learned about the use of "would" is almost virtually useless, as this word has a bewildering multiplicity of uses.

One use is in the subjunctive, in a contrary-to-fact statement, the word "would" expresses the consequences in this contrary-to-fact world. Your first statement is an example of this.
1) If I had \$10M, I would buy a luxury car. = correct statement in the subjunctive

Another correct use involves somebody's speculation of a future possibility. Your second statement is correct in this sense:
2) The scientist believes that such a machine would be wonderful. = also 100% correct

Another use is as the future tense from the perspective of a speaker in the past, when using sequence of tenses.
3) By the summer of 1824, Beethoven felt that he had said all he wanted to say in symphonic form, but that he still would have more to say in the string quartet format.

Another use, admittedly somewhat less likely to show up on the GMAT, is as an expression of preference, often considered gracious and polite.
4) I would be interested to find out more about your trip.

All five of these are 100% correct. It's very hard to make a simple rule for "would."

Does all this make sense?
Mike
_________________
Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)
Manager
Joined: 05 Dec 2014
Posts: 198
Location: India
GMAT 1: 690 Q48 V36
GPA: 3.54
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

04 Dec 2017, 22:20
mikemcgarry wrote:
sunny91 wrote:

Hi Mike,
option d looks the best. But I have a query with the use of would. Would is used correctly when there is a reference of another past event.
Ex- If I had 10 million \$, I would buy the luxury car.
Ex- The scientist believes that the machine would be wonderful.

The above example is wrong as 'believes' is in present. If believes is replaced by 'believed' the ex becomes correct.
Again, if we the have the sentence- I would buy the car, this sentence is wrong as we dont have a clear past event reference.
Now, in option D, would have to know a great deal more than they do now about the social and economical- here do is in present tense and so how can we ignore the past tense reference.

Dear sunny91,

I'm happy to respond.

My friend, many student labor under the misconception that one can arrive at GMAT SC mastery by memorizing some mythical "complete" set of grammar rules. This rule-based approach to the GMAT SC is doomed to failure. Yes, there are some important rules, and it's important to know those--for example, SVA. Nevertheless, many patterns in language are much more complex and demand broad intuition about the language. The only way a non-native speaker develops this intuition is through the habit of reading. See:
How to Improve Your GMAT Verbal Score

I would say that any rule you have learned about the use of "would" is almost virtually useless, as this word has a bewildering multiplicity of uses.

One use is in the subjunctive, in a contrary-to-fact statement, the word "would" expresses the consequences in this contrary-to-fact world. Your first statement is an example of this.
1) If I had \$10M, I would buy a luxury car. = correct statement in the subjunctive

Another correct use involves somebody's speculation of a future possibility. Your second statement is correct in this sense:
2) The scientist believes that such a machine would be wonderful. = also 100% correct

Another use is as the future tense from the perspective of a speaker in the past, when using sequence of tenses.
3) By the summer of 1824, Beethoven felt that he had said all he wanted to say in symphonic form, but that he still would have more to say in the string quartet format.

Another use, admittedly somewhat less likely to show up on the GMAT, is as an expression of preference, often considered gracious and polite.
4) I would be interested to find out more about your trip.

All five of these are 100% correct. It's very hard to make a simple rule for "would."

Does all this make sense?
Mike

Hi Mike,
Thanks for the response. Sorry to say, but I am still not very clear. I know that usage of would in case of desire/purpose avoid past reference. Example- I would like to have some tea.
Otherwise, in conditional/subjunctive case, we use a past reference. Now, u mentioned that the below sentence is 100% correct.
The scientist believes that such a machine would be wonderful. This is another correct use involves somebody's speculation of a future possibility.

My question is in logical terms whats is the difference in meaning
The scientist believes that such a machine would be wonderful. The scientist believed that such a machine would be wonderful.
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4487
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

05 Dec 2017, 15:21
1
sunny91 wrote:
Hi Mike,
Thanks for the response. Sorry to say, but I am still not very clear. I know that usage of would in case of desire/purpose avoid past reference. Example- I would like to have some tea.
Otherwise, in conditional/subjunctive case, we use a past reference. Now, u mentioned that the below sentence is 100% correct.
The scientist believes that such a machine would be wonderful. This is another correct use involves somebody's speculation of a future possibility.

My question is in logical terms whats is the difference in meaning
The scientist believes that such a machine would be wonderful. The scientist believed that such a machine would be wonderful.

Dear sunny91,

I'm happy to respond. The difference concerns whether the future item is viewed as a sure thing or is speculative.

Case I: future event is viewed as factual and certain
present:
1) The general believes that the enemy will attack from the south.
past:
2) The general believed that the enemy would attack from the south.
There, "would" is just the past tense of "will." In both cases, the general was viewing the attack as something guaranteed to to happen, from his point of view. Since #2 is in the past, it might be followed by a factual statement of what actually did happen.

Case II: future event is hypothetical or contrary-to-fact.
present:
3) The general believes that the enemy would attack from the south.
That sentence is correct, but it provokes the question: why doesn't the enemy attach from the south?
This might also appear with an explanatory conditional:
4) The general believes that the enemy would attack from the south if it can cover all that ground in such a short time.
In other words, we are expecting the result if the condition is met, but overall, we are still doubtful that this condition will be met.

It's much harder to talk about what was hypothetical in the past. I guarantee that the GMAT will not be interested in testing that.

Once again, I cannot emphasize enough how much the habit of reading can help with dozens and dozens of questions of this sort. Once you develop intuition for all these words in context, much will become clear. I recommend that blog linked in my previous post.

Does all this make sense?
Mike
_________________
Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)
SVP
Status: It's near - I can see.
Joined: 13 Apr 2013
Posts: 1686
Location: India
GPA: 3.01
WE: Engineering (Real Estate)
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

30 Mar 2018, 10:18
english_august wrote:
To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

(A) have to know a great deal more than now about the social and economic
(B) have to know a great deal more than they do now about the social and economical
(C) would have to know a great deal more than they do now about the social and economical
(D) would have to know a great deal more than they do now about the social and economic
(E) would have to know a great deal more than now about the social and economic

(A) have to know a great deal more than now about the social and economic

(B) have to know a great deal more than they do now about the social and economical

(C) would have to know a great deal more than they do now about the social and economical

(D) would have to know a great deal more than they do now about the social and economic

(E) would have to know a great deal more than now about the social and economic

(D)
_________________
"Do not watch clock; Do what it does. KEEP GOING."
EMPOWERgmat Instructor
Joined: 23 Feb 2015
Posts: 497
To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

Updated on: 23 Mar 2019, 12:11
1
Hello Everyone!

Let's tackle this question, one issue at a time, and come up with the correct choice! First, let's take a quick look at the original question, and highlight any major differences between the options in orange:

To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

(A) have to know a great deal more than now about the social and economic
(B) have to know a great deal more than they do now about the social and economical
(C) would have to know a great deal more than they do now about the social and economical
(D) would have to know a great deal more than they do now about the social and economic
(E) would have to know a great deal more than now about the social and economic

After a quick glance over the options, we see a few places we can focus on:

1. have to know / would have to know
2. now / they do now
3. economic / economical

Let's start with #3 on our list: economic vs. economical. This is an easy way to eliminate 2-3 options because it's a common mistake we see on the GMAT:

economic = dealing with the economy
economical = inexpensive, cheap, thrifty, etc.

Since the sentence is talking about the economy, we can eliminate options B & C because they use the word "economical," which isn't the correct word for this sentence. That was quick, right?

Let's move up to #2 on the list: now vs. they do now. Here are the remaining sentences with the non-underlined parts added in to better catch any problems:

(A) To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

This is INCORRECT because it creates a non-parallel comparison. We are supposed to compare what demographers would have to know (knowledge) to what demographers know now (knowledge). This is comparing what demographers would have to know (knowledge) to now (time), which isn't parallel!
(This is also wrong because "have to know" isn't how to write a conditional statement. "Would have to know" is a condition, which would make this a conditional statement.)

(D) To develop more accurate population forecasts, demographers would have to know a great deal more than they do now about the social and economic determinants of fertility.

This is CORRECT! It compares what demographers would have to know (knowledge) to what they know now (knowledge), which is parallel! It's also best to use "would have to know" to indicate this is a conditional statement, and it does that correctly!

(E) To develop more accurate population forecasts, demographers would have to know a great deal more than now about the social and economic determinants of fertility.

This is INCORRECT because it creates a non-parallel comparison. We are supposed to compare what demographers would have to know (knowledge) to what demographers know now (knowledge). This is comparing what demographers would have to know (knowledge) to now (time), which isn't parallel!

There you have it - option D is the correct choice! Even if you weren't confident on how to deal with conditional statements and verb tenses, you could still answer this question by focusing on parallel comparisons and proper word usage!

Don't study for the GMAT. Train for it.
_________________

Originally posted by EMPOWERgmatVerbal on 06 Nov 2018, 16:33.
Last edited by EMPOWERgmatVerbal on 23 Mar 2019, 12:11, edited 1 time in total.
Director
Joined: 29 Jun 2017
Posts: 773
Re: To develop more accurate population forecasts, demographers  [#permalink]

### Show Tags

29 Dec 2018, 09:10
pls, explain the difference among the followings
to go to us, I would have to learn English
to go to us, I have to learn English
to go to us, I will have to learn English

and pls, tell whether the following is correct

I would have to learn gmat harder tomorrow than today

if this is correct, why choice A which containes " than today" is correct?

thanks.
Re: To develop more accurate population forecasts, demographers   [#permalink] 29 Dec 2018, 09:10

Go to page   Previous    1   2   [ 37 posts ]

Display posts from previous: Sort by