BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Some amount of money is invested in an account at \(r\) percent compound interest rate, the amount of investment will

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 2898
Joined: Thu Sep 07, 2017 2:49 pm
Thanked: 6 times
Followed by:5 members

Some amount of money is invested in an account at \(r\) percent compound interest rate, the amount of investment will

by Vincen » Wed Nov 18, 2020 10:59 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

Some amount of money is invested in an account at \(r\) percent compound interest rate, the amount of investment will double in \(\dfrac{70}{r}\) years. If the amount gets \(4\) times in \(‘‘n"\) years, is \(n < 10?\)

(1) \(r < 14\%\)
(2) \(r > 12\%\)

Answer: A

Source: e-GMAT
Top
Source: — Data Sufficiency |
Legendary Member
Posts: 2214
Joined: Fri Mar 02, 2018 2:22 pm
Followed by:5 members

Re: Some amount of money is invested in an account at \(r\) percent compound interest rate, the amount of investment wil

by deloitte247 » Thu Nov 19, 2020 10:59 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

$$2p=p\left(1+\frac{r}{100}\right)^{\frac{70}{r}}$$
$$\left(\left(2\right)^2=\left(1+\frac{r}{100}\right)^{\frac{70}{r}}\right)^2$$
$$if=\left(1+\frac{r}{100}\right)^{\frac{140}{r}}$$
so amount of investment doubles in 70/r years but 140/r years will make the amount 4 times, hence n = 140/r
$$1\ is\ \frac{140}{r}<10\ =\ r>14$$


$$Statement\ 1\ =>\ r<14\%$$
This provides a definite answer to the target question hence statement 1 is SUFFICIENT

$$Statement\ 2=>r>12\%$$
The value of r can either be 13 which is less than 1.4 or 15 which is greater than 14, so there is no definite answer to the target question hence statement 2 is NOT SUFFICIENT.


Since only statement 1 is SUFFICIENT,
Answer = A
Top
Post new topic Post Reply
• Page 1 of 1