It is currently 25 Jun 2017, 17:56

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# If money is invested at r percent interest, compounded

Author Message
Manager
Joined: 10 Dec 2007
Posts: 53
If money is invested at r percent interest, compounded [#permalink]

### Show Tags

20 Jan 2008, 10:37
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If money is invested at r percent interest, compounded annually, the amount of the investment will double in approx.70/r years.If pat's parents invested $5'000 in a long term bond that pays 8 percent interest, compounded annually, what will be the approx total amount of the investment 18 years later, when Pat is ready for college? A.$20,000
B. $15,000 C.$12,000
D. $10,000 E.$9,000

-thanx
Director
Joined: 01 Jan 2008
Posts: 622

### Show Tags

20 Jan 2008, 11:51
4 = 8%, double in 70/8 = 35/4 = 8.75, quadriple in 17.5 years. 5*4 = 20, A is the answer.
Manager
Joined: 20 Sep 2007
Posts: 106

### Show Tags

20 Jan 2008, 11:54

Expln : 2P = P ( 1+ r/100)^70/r As per coumpond interest on value P after 70/r years

2= ( 1+ r/100 ) ^ 70/r

Now for 18 years problem final amount = 5000(1+8/100)^18
Put r=8 in above equation and (1+8/100)^9 appx equal to 2
so final amount is 5000 x 2 x 2 =20000
Intern
Joined: 08 Jan 2007
Posts: 17

### Show Tags

21 Jan 2008, 11:02
I say A

if 70/8 means it will double app every 9 years

then it will be 10000 at year 9
and 2 of 10000 will be 20000 at year 18
Re: money   [#permalink] 21 Jan 2008, 11:02
Display posts from previous: Sort by