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In a certain population, the two most heavily diagnosed [#permalink]

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24 Apr 2013, 10:01

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In a certain population, the two most heavily diagnosed diseases are schistosomiasis and malaria. Over the past five years, malaria has accounted for more than half of all disease cases, and schistosomiasis, which accounted for 40% of all disease cases in the community five years ago, accounted for 30% in the past year.

Which of the following must be true on the basis of the statements above?

A) There were fewer cases of schistosomiasis last year than five years ago. B) The percentage of disease cases from malaria has increased over the past 5 years. C) Some disease has experienced an increase in the number of its total cases, as long as the total number of disease cases went down by a number less than 30%. D) Each year over the past five, malaria has accounted for a larger percentage of disease cases than schistosomiasis. E) If the total number of schistosomiasis cases increased over the past five years, then the total number of disease cases must have increased by more than 30%.

Re: In a certain population, the two most heavily diagnosed dise [#permalink]

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24 Apr 2013, 10:45

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its E : think like this : if initially the total number of disease were 100 then S accounted for 40 case now if increase these cases of S even to 41 then total number of cases of disease must be made to around 136 ----> which means that total number of diseases have increased by more than 30 percent !!

Re: In a certain population, the two most heavily diagnosed dise [#permalink]

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24 Apr 2013, 14:34

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In a certain population, the two most heavily diagnosed diseases are schistosomiasis and malaria. Over the past five years, malaria has accounted for more than half of all disease cases, and schistosomiasis, which accounted for 40% of all disease cases in the community five years ago, accounted for 30% in the past year.

Which of the following must be true on the basis of the statements above?

A) There were fewer cases of schistosomiasis last year than five years ago. Wrong. The fact that the percentage is less than that in the past does not mean the absolute value is also less. ==> Eliminate right away.

B) The percentage of disease cases from malaria has increased over the past 5 years. Wrong. No information of percentage of disease cases from malaria in the past ==> Eliminate right away.

C) Some disease has experienced an increase in the number of its total cases, as long as the total number of disease cases went down by a number less than 30%. Wrong. Quite confused. However, it's wrong because of "some disease" is not clear. In this question, we just talk about Malaria and schistosomiasis.

D) Each year over the past five, malaria has accounted for a larger percentage of disease cases than schistosomiasis. Wrong. Shell game. But it's wrong because it says "Each year".

E) If the total number of schistosomiasis cases increased over the past five years, then the total number of disease cases must have increased by more than 30%. Correct. five years ago, the number of schistosomiasis cases was 40/100 total number of disease cases (40%). Last year, the number of schistosomiasis was 60 ==> Total number of disease cases was (60 /30%)x100% = 200 ==> Total disease cases increased 100% that is more than 30%.
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If the percentage of cases has dropped from 40 to 30, that means there are 3/4 as many cases per 100 as there were before. In order for the actual number to go up, there needs to be an increase in the total disease cases of more than 4/3. (3/4 x 4/3 = 1, so anything greater than 4/3 will lead to an increase.) This means that for the # of cases of schistosomiasis to go up, we need an increase of more than 1/3. E is correct.

C, on the other hand, is saying something that *seems* kind of sensible. If the % of schistosomiasis cases goes down, and the total number doesn't drop drastically, then doesn't something else need to go down? The answer is no. If schistosomiasis goes down, and everything else stays the same, it can represent 30% of all cases without anything else having to go up. This leads to a drop in total cases of about 15%.

To illustrate, imagine that the original breakdown is like this: 51 cases of malaria, 40 cases of schistosomiasis, and 9 cases of flu. What # of schistosomiasis cases would yield a new % of 30 if the # of malaria and flu cases stay the same? Schist/Total = s/(51+9+s) = .30 s = .3(60 + s) .7s = 18 s is about 25, so the new total is about 85, which is just a 15% drop.

Don't you love doing algebra in the verbal section? :/
_________________

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Re: In a certain population, the two most heavily diagnosed [#permalink]

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03 Jul 2014, 06:29

Hello from the GMAT Club VerbalBot!

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Re: In a certain population, the two most heavily diagnosed [#permalink]

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13 Jul 2014, 01:00

manugmat123 wrote:

In a certain population, the two most heavily diagnosed diseases are schistosomiasis and malaria. Over the past five years, malaria has accounted for more than half of all disease cases, and schistosomiasis, which accounted for 40% of all disease cases in the community five years ago, accounted for 30% in the past year.

Which of the following must be true on the basis of the statements above?

A) There were fewer cases of schistosomiasis last year than five years ago. B) The percentage of disease cases from malaria has increased over the past 5 years. C) Some disease has experienced an increase in the number of its total cases, as long as the total number of disease cases went down by a number less than 30%. D) Each year over the past five, malaria has accounted for a larger percentage of disease cases than schistosomiasis. E) If the total number of schistosomiasis cases increased over the past five years, then the total number of disease cases must have increased by more than 30%.

As soon as we see %, there will be some catch with total number of cases. A) There were fewer cases of schistosomiasis last year than five years ago - Cannot be inferred B) The percentage of disease cases from malaria has increased over the past 5 years - Cannot be inferred C) Some disease has experienced an increase in the number of its total cases, as long as the total number of disease cases went down by a number less than 30%. This is not possible as "S" % wise went down, so if the total number of cases of "S" went up, the total number of all cases has to go up and not down

D) Each year over the past five, malaria has accounted for a larger percentage of disease cases than schistosomiasis We don't have each year data, cannot be infered E) If the total number of schistosomiasis cases increased over the past five years, then the total number of disease cases must have increased by more than 30%. Looks ok. Calculation wise. 5 years back for "S" disease 100 Total cases - "S" disease - 40 - Percentage = 40% if we have to maintain the same cases Percentage = 30% "S" disease cases = 40 Then total should be close to 130 as 13*3 = 39 Hence Option E) _________________

Re: In a certain population, the two most heavily diagnosed [#permalink]

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13 Jul 2015, 03:03

Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: In a certain population, the two most heavily diagnosed [#permalink]

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17 Jul 2015, 04:37

DmitryFarber wrote:

How about a fraction approach?

If the percentage of cases has dropped from 40 to 30, that means there are 3/4 as many cases per 100 as there were before. In order for the actual number to go up, there needs to be an increase in the total disease cases of more than 4/3. (3/4 x 4/3 = 1, so anything greater than 4/3 will lead to an increase.) This means that for the # of cases of schistosomiasis to go up, we need an increase of more than 1/3. E is correct.

C, on the other hand, is saying something that *seems* kind of sensible. If the % of schistosomiasis cases goes down, and the total number doesn't drop drastically, then doesn't something else need to go down? The answer is no. If schistosomiasis goes down, and everything else stays the same, it can represent 30% of all cases without anything else having to go up. This leads to a drop in total cases of about 15%.

To illustrate, imagine that the original breakdown is like this: 51 cases of malaria, 40 cases of schistosomiasis, and 9 cases of flu. What # of schistosomiasis cases would yield a new % of 30 if the # of malaria and flu cases stay the same? Schist/Total = s/(51+9+s) = .30 s = .3(60 + s) .7s = 18 s is about 25, so the new total is about 85, which is just a 15% drop.

Don't you love doing algebra in the verbal section? :/

Hello Dmitry, Could you please explain I could get this part If the percentage of cases has dropped from 40 to 30, that means there are 3/4 as many cases per 100 as there were before But after 4/3 is of what (number of total number of cases before or now ) ? Thanks

Re: In a certain population, the two most heavily diagnosed [#permalink]

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17 Jul 2015, 04:38

DmitryFarber wrote:

How about a fraction approach?

If the percentage of cases has dropped from 40 to 30, that means there are 3/4 as many cases per 100 as there were before. In order for the actual number to go up, there needs to be an increase in the total disease cases of more than 4/3. (3/4 x 4/3 = 1, so anything greater than 4/3 will lead to an increase.) This means that for the # of cases of schistosomiasis to go up, we need an increase of more than 1/3. E is correct.

C, on the other hand, is saying something that *seems* kind of sensible. If the % of schistosomiasis cases goes down, and the total number doesn't drop drastically, then doesn't something else need to go down? The answer is no. If schistosomiasis goes down, and everything else stays the same, it can represent 30% of all cases without anything else having to go up. This leads to a drop in total cases of about 15%.

To illustrate, imagine that the original breakdown is like this: 51 cases of malaria, 40 cases of schistosomiasis, and 9 cases of flu. What # of schistosomiasis cases would yield a new % of 30 if the # of malaria and flu cases stay the same? Schist/Total = s/(51+9+s) = .30 s = .3(60 + s) .7s = 18 s is about 25, so the new total is about 85, which is just a 15% drop.

Don't you love doing algebra in the verbal section? :/

Hello Dmitry, Could you please explain I could get this part If the percentage of cases has dropped from 40 to 30, that means there are 3/4 as many cases per 100 as there were before But after 4/3 is of what (number of total number of cases before or now ) ? Thanks

Re: In a certain population, the two most heavily diagnosed [#permalink]

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08 Aug 2015, 06:00

I got this question correct. Eliminated A B D. B/w C and E, without algebra I got the hint that what E is trying to say.

C talks about other disease. so eliminated.

I would still like to know what option C says. I could not comprehend this option in exam. Even now I am not able to understand whats its trying to say. I could still not understand from above answer what C means.

In a certain population, the two most heavily diagnosed [#permalink]

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14 Aug 2015, 07:53

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manugmat123 wrote:

In a certain population, the two most heavily diagnosed diseases are schistosomiasis and malaria. Over the past five years, malaria has accounted for more than half of all disease cases, and schistosomiasis, which accounted for 40% of all disease cases in the community five years ago, accounted for 30% in the past year.

Which of the following must be true on the basis of the statements above?

A) There were fewer cases of schistosomiasis last year than five years ago. B) The percentage of disease cases from malaria has increased over the past 5 years. C) Some disease has experienced an increase in the number of its total cases, as long as the total number of disease cases went down by a number less than 30%. D) Each year over the past five, malaria has accounted for a larger percentage of disease cases than schistosomiasis. E) If the total number of schistosomiasis cases increased over the past five years, then the total number of disease cases must have increased by more than 30%.

E basically says-(if..hypothetical.....)

If 40% x < 30 % y , (where x = total cases 5 years ago and y= total cases in past year)

then ( y-x )/x > 1/3 ( after solving the inequality stated )

hence , increase IN TOTAL number of cases has been more than 33.3 % ( 33.33% is more than 30 %)

The above can be true based on the argument.

Hope the simple inequality helps state why E is right.

I DONOT MIND KUDOS _________________

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Re: In a certain population, the two most heavily diagnosed [#permalink]

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23 Aug 2016, 07:19

I have a small doubt in this question and i request people to clarify ,

I chose option D and was wrong . It is mentioned in the premise that " Over the past five years, malaria has accounted for more than half of all disease cases " , so i inferred that every year malaria has accounted for more than 50% of the cases . cant we conclude that " Over the past 5 years " means all the years within the range of those 5 years ?

because if we can conclude that Malaria did account for more than 50% for all 5 years , then schistosomiasis would naturally account for less than 50% over these years and then we can easily conclude that option D would be correct

Re: In a certain population, the two most heavily diagnosed [#permalink]

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23 Aug 2016, 09:32

rohitmilind007ster wrote:

I have a small doubt in this question and i request people to clarify ,

I chose option D and was wrong . It is mentioned in the premise that " Over the past five years, malaria has accounted for more than half of all disease cases " , so i inferred that every year malaria has accounted for more than 50% of the cases . cant we conclude that " Over the past 5 years " means all the years within the range of those 5 years ?

because if we can conclude that Malaria did account for more than 50% for all 5 years , then schistosomiasis would naturally account for less than 50% over these years and then we can easily conclude that option D would be correct

It says "over the past five years,...cases" --> average is more than 50 % not each year. One year it can be 99% and other year it can be less than 30%. The number varies but average is more than 50%. I also fell in to this trap.

Re: In a certain population, the two most heavily diagnosed [#permalink]

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24 Aug 2016, 23:47

In a certain population, the two most heavily diagnosed diseases are schistosomiasis and malaria. Over the past five years, malaria has accounted for more than half of all disease cases, and schistosomiasis, which accounted for 40% of all disease cases in the community five years ago, accounted for 30% in the past year.

Over the past five years

S m others 50>

five years ago S m others 40%

past year S m others 30%

Which of the following must be true on the basis of the statements above?

B) The percentage of disease cases from malaria has increased over the past 5 years.

You don't know total cases of disease before 5 year & over the past 5 years. This would have been true if total cases of disease equal for both cases.

D) Each year over the past five, malaria has accounted for a larger percentage of disease cases than schistosomiasis.

We know about over the past year thing but we don't have any info about each year individually.

E) If the total number of schistosomiasis cases increased over the past five years, then the total number of disease cases must have increased by more than 30%.

assume total no. of disease are same, it's possible that total number of schistosomiasis cases increased over the past five years increases anyway.

In a certain population, the two most heavily diagnosed [#permalink]

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25 Aug 2016, 06:20

abrakadabra21 wrote:

In a certain population, the two most heavily diagnosed diseases are schistosomiasis and malaria. Over the past five years, malaria has accounted for more than half of all disease cases, and schistosomiasis, which accounted for 40% of all disease cases in the community five years ago, accounted for 30% in the past year.

Over the past five years

S m others 50>

five years ago S m others 40%

past year S m others 30%

Which of the following must be true on the basis of the statements above?

B) The percentage of disease cases from malaria has increased over the past 5 years.

You don't know total cases of disease before 5 year & over the past 5 years. This would have been true if total cases of disease equal for both cases.

D) Each year over the past five, malaria has accounted for a larger percentage of disease cases than schistosomiasis.

We know about over the past year thing but we don't have any info about each year individually.

E) If the total number of schistosomiasis cases increased over the past five years, then the total number of disease cases must have increased by more than 30%.

assume total no. of disease are same, it's possible that total number of schistosomiasis cases increased over the past five years increases anyway.

Over the past five years

S m others 50>

five years ago S m others 40%

How E is correct?

Lets assume total number of schistosomiasis cases remained same.

Let those cases be 100.

Now, 5 years ago, such cases were 40% or 40.

Past year, such cases were 30% = 30.

But as per E, it says if we increase such cases. But as per the scenario we have taken, we are actually decreasing such cases.

Hence, Total cannot be the same.

So, if I say 5 years it was 100 and S cases were 40. I must assume that past year such an increase would have been atleast 41.

So, we have 41 = 30% of total.

or Total = 136.

So, you can see we have an increase of 36 or 36%.

Hence, an increase of atleast 30%. So, E is correct.
_________________

Re: In a certain population, the two most heavily diagnosed [#permalink]

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13 Sep 2016, 08:21

In a certain population, the two most heavily diagnosed diseases are schistosomiasis and malaria. Over the past five years, malaria has accounted for more than half of all disease cases, and schistosomiasis, which accounted for 40% of all disease cases in the community five years ago, accounted for 30% in the past year.

Notice the pattern of data given. Data regarding malaria is given over a time whereas data at two times is given for Schisto.....

Which of the following must be true on the basis of the statements above?

A) There were fewer cases of schistosomiasis last year than five years ago........Percentage reduction from 40% to 30% cannot infer the number of cases. We need population data as well.

B) The percentage of disease cases from malaria has increased over the past 5 years.......were given overall data for past 5yrs i.e., more than 50% but no info is given regarding change either increase or decrease.

C) Some disease has experienced an increase in the number of its total cases, as long as the total number of disease cases went down by a number less than 30%.............This choice seems really vague. Keep it aside.

D) Each year over the past five, malaria has accounted for a larger percentage of disease cases than schistosomiasis........In case of malaria we have overall data for 5 years so we cannot say this.

E) If the total number of schistosomiasis cases increased over the past five years, then the total number of disease cases must have increased by more than 30%............Left over choice and makes a bit sense more than C or nay other choices. This picked out of POE. Pick numbers as total disease population say TDP 5yrs back is 100 Schi cases are 40 last yr Schi cases are increased to say >40 = 42(since 41 is not mutiple of 3) 42=30%TDP last yr TDP= 140

difference in TDP is from 100 to 140 is 40% (which is more than 30%)
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Re: In a certain population, the two most heavily diagnosed [#permalink]

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14 Sep 2016, 14:50

chaitanya87 wrote:

rohitmilind007ster wrote:

I have a small doubt in this question and i request people to clarify ,

I chose option D and was wrong . It is mentioned in the premise that " Over the past five years, malaria has accounted for more than half of all disease cases " , so i inferred that every year malaria has accounted for more than 50% of the cases . cant we conclude that " Over the past 5 years " means all the years within the range of those 5 years ?

because if we can conclude that Malaria did account for more than 50% for all 5 years , then schistosomiasis would naturally account for less than 50% over these years and then we can easily conclude that option D would be correct

It says "over the past five years,...cases" --> average is more than 50 % not each year. One year it can be 99% and other year it can be less than 30%. The number varies but average is more than 50%. I also fell in to this trap.

No where average term is used in argument. Many said that Each in the (D) is wrong, but when argument clearly says malaria has accounted for more than 50% in the past 5 years Need clear reason why D is wrong or better than E.

In a certain population, the two most heavily diagnosed [#permalink]

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14 Sep 2016, 19:35

ravikrishna1979 wrote:

No where average term is used in argument. Many said that Each in the (D) is wrong, but when argument clearly says malaria has accounted for more than 50% in the past 5 years Need clear reason why D is wrong or better than E.

For example salary package of prev 5 yrs in an mnc is as follows yr1: 3LPA yr2: 4LPA(increment) yr3: 3LPA(salary reduced due to lower band..............it happens trust me) yr4 and 5: Resigned and unemployed for 2 yrs

Overall salary is 2LPA

But can we say each year your salary was more than some X's say 10K. No right yr4 and 5 you did not have a salary and cannot have more salary than 10K.

Now option D SAYS

Quote:

Each year over the past five, malaria has accounted for a larger percentage of disease cases than schistosomiasis.

Isnt the scenario same? So D is incorrect for same reason.

I hope this helps _________________

The only time you can lose is when you give up. Try hard and you will suceed. Thanks = Kudos. Kudos are appreciated

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