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 Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

The annual birth and death rate in a country per 1000 are 39.4 and 19. [#permalink]

Show Tags

20 Oct 2010, 04:43

1

This post received KUDOS

4

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

75% (hard)

Question Stats:

48% (03:32) correct
52% (02:11) wrong based on 62 sessions

HideShow timer Statistics

The annual birth and death rate in a country per 1000 are 39.4 and 19.4 respectively . the number of years in which the population would be doubled assuming there is no emigration or immigration is

Re: The annual birth and death rate in a country per 1000 are 39.4 and 19. [#permalink]

Show Tags

20 Oct 2010, 05:03

anilnandyala wrote:

the annual birth and death rate in a country per 1000 are 39.4 and 19.4 respectively . the number of years in which the population would be doubled assuming there is no emigration or immigration is a 20 b 25 c 30 d 35 e 40

Suppose the population of the country in current year is 1000. So annual increase is 1000 + 39.4 - 19.4=1020 Hence every year there is an increase of 2%.

2000=1000(1+(2/100))^n

n=35 Answer is D. (But Calculation is somewhat tedious.) Anything simple than this?

Re: The annual birth and death rate in a country per 1000 are 39.4 and 19. [#permalink]

Show Tags

20 Oct 2010, 05:28

ankitranjan wrote:

Suppose the population of the country in current year is 1000. So annual increase is 1000 + 39.4 - 19.4=1020 Hence every year there is an increase of 2%.

2000=1000(1+(2/100))^n

n=35 Answer is D. (But Calculation is somewhat tedious.) Anything simple than this?

Consider KUDOS if its helpful.

Yes, I also solved it in that way. The problem is that you cannot use a scientific calculator during the exam LOL. I think we need the help of the moderators! _________________

"Life’s battle doesn’t always go to stronger or faster men; but sooner or later the man who wins is the one who thinks he can."

My Integrated Reasoning Logbook / Diary: http://gmatclub.com/forum/my-ir-logbook-diary-133264.html

Re: The annual birth and death rate in a country per 1000 are 39.4 and 19. [#permalink]

Show Tags

17 Mar 2015, 11:46

3

This post received KUDOS

2

This post was BOOKMARKED

An easier method is the Rule of 70 which is a simple way to calculate the approximate number of years it takes for the level of a variable growing at a constant rate to double. This rule states that the approximate number of years n for a variable growing at the constant growth rate of R percent, to double is

n = 70/R

Since B-D = 39.4-19.4 = 20 normalized to 1000 = 2%

Re: The annual birth and death rate in a country per 1000 are 39.4 and 19. [#permalink]

Show Tags

17 Mar 2015, 13:25

1

This post received KUDOS

1

This post was BOOKMARKED

kcr2210 wrote:

An easier method is the Rule of 70 which is a simple way to calculate the approximate number of years it takes for the level of a variable growing at a constant rate to double. This rule states that the approximate number of years n for a variable growing at the constant growth rate of R percent, to double is

n = 70/R

Since B-D = 39.4-19.4 = 20 normalized to 1000 = 2%

The n = 70/2 = 35

wow! I have never heard about this, interesting... Do you have any support to prove this approach will always show me the right answer?

An easier method is the Rule of 70 which is a simple way to calculate the approximate number of years it takes for the level of a variable growing at a constant rate to double. This rule states that the approximate number of years n for a variable growing at the constant growth rate of R percent, to double is

n = 70/R

Since B-D = 39.4-19.4 = 20 normalized to 1000 = 2%

The n = 70/2 = 35

wow! I have never heard about this, interesting... Do you have any support to prove this approach will always show me the right answer?

Thank you for your reply.

You can use the n = 70/r rule whenever you want the amount to double in an annual compounded interest rate scenario but GMAT doesn't expect you to know this formula so the calculations will either be simpler or the formula will be given in the question. _________________

Re: The annual birth and death rate in a country per 1000 are 39.4 and 19. [#permalink]

Show Tags

18 Mar 2015, 22:29

kcr2210 wrote:

An easier method is the Rule of 70 which is a simple way to calculate the approximate number of years it takes for the level of a variable growing at a constant rate to double. This rule states that the approximate number of years n for a variable growing at the constant growth rate of R percent, to double is

n = 70/R

Since B-D = 39.4-19.4 = 20 normalized to 1000 = 2%

The n = 70/2 = 35

Kudos to you !! Good one . _________________

Thanks, Lucky

_______________________________________________________ Kindly press the to appreciate my post !!

Re: The annual birth and death rate in a country per 1000 are 39.4 and 19. [#permalink]

Show Tags

16 Apr 2015, 03:30

metallicafan wrote:

ankitranjan wrote:

Suppose the population of the country in current year is 1000. So annual increase is 1000 + 39.4 - 19.4=1020 Hence every year there is an increase of 2%.

2000=1000(1+(2/100))^n

n=35 Answer is D. (But Calculation is somewhat tedious.) Anything simple than this?

Consider KUDOS if its helpful.

Yes, I also solved it in that way. The problem is that you cannot use a scientific calculator during the exam LOL. I think we need the help of the moderators!

Can anyone guide me how to solve this manually.I don't have any clue.

Suppose the population of the country in current year is 1000. So annual increase is 1000 + 39.4 - 19.4=1020 Hence every year there is an increase of 2%.

2000=1000(1+(2/100))^n

n=35 Answer is D. (But Calculation is somewhat tedious.) Anything simple than this?

Consider KUDOS if its helpful.

Yes, I also solved it in that way. The problem is that you cannot use a scientific calculator during the exam LOL. I think we need the help of the moderators!

Can anyone guide me how to solve this manually.I don't have any clue.

2000=1000(1+(2/100))^n

You cannot solve it manually. You need a calculator to do it. Though, when the amount is twice the principal, we have a simple formula (which will be given in the question if this question comes in GMAT) The principal doubles in 70/r years. Since the rate of interest is 2% here, and the principal doubles from 1000 to 2000, the number of years it will take is 70/2 = 35 years. _________________

Re: The annual birth and death rate in a country per 1000 are 39.4 and 19. [#permalink]

Show Tags

17 Apr 2015, 04:35

VeritasPrepKarishma wrote:

ssriva2 wrote:

metallicafan wrote:

Suppose the population of the country in current year is 1000. So annual increase is 1000 + 39.4 - 19.4=1020 Hence every year there is an increase of 2%.

2000=1000(1+(2/100))^n

n=35 Answer is D. (But Calculation is somewhat tedious.) Anything simple than this?

Consider KUDOS if its helpful.

Yes, I also solved it in that way. The problem is that you cannot use a scientific calculator during the exam LOL. I think we need the help of the moderators!

Can anyone guide me how to solve this manually.I don't have any clue.

2000=1000(1+(2/100))^n

You cannot solve it manually. You need a calculator to do it. Though, when the amount is twice the principal, we have a simple formula (which will be given in the question if this question comes in GMAT) The principal doubles in 70/r years. Since the rate of interest is 2% here, and the principal doubles from 1000 to 2000, the number of years it will take is 70/2 = 35 years.[/quote]

Thanks a lot Karishma.I usually get struck on this last part in these kind of questions.

gmatclubot

Re: The annual birth and death rate in a country per 1000 are 39.4 and 19.
[#permalink]
17 Apr 2015, 04:35

Check out this awesome article about Anderson on Poets Quants, http://poetsandquants.com/2015/01/02/uclas-anderson-school-morphs-into-a-friendly-tech-hub/ . Anderson is a great place! Sorry for the lack of updates recently. I...

As you leave central, bustling Tokyo and head Southwest the scenery gradually changes from urban to farmland. You go through a tunnel and on the other side all semblance...

Ghibli studio’s Princess Mononoke was my first exposure to Japan. I saw it at a sleepover with a neighborhood friend after playing some video games and I was...