Bank interest rate questions

This topic has expert replies
Junior | Next Rank: 30 Posts
Posts: 24
Joined: Mon Nov 29, 2010 3:46 pm

Bank interest rate questions

by neilcao » Mon Feb 21, 2011 7:23 am
2% compound interest,no money put in and out in 10 years,the interests for two years is 5050, what's the original amount of money

Master | Next Rank: 500 Posts
Posts: 139
Joined: Fri Nov 26, 2010 4:45 pm
Location: Boston
Thanked: 20 times
Followed by:1 members
GMAT Score:720

by stormier » Mon Feb 21, 2011 7:27 am
neilcao wrote:2% compound interest,no money put in and out in 10 years,the interests for two years is 5050, what's the original amount of money
This is an incomplete question. One needs to know whether the interest was compounded quarterly, annually, monthly, or ...

Senior | Next Rank: 100 Posts
Posts: 58
Joined: Fri Oct 22, 2010 1:05 am
Location: Bhopal
Thanked: 1 times
GMAT Score:710

by mk101 » Mon Feb 21, 2011 7:39 am
neilcao wrote:2% compound interest,no money put in and out in 10 years,the interests for two years is 5050, what's the original amount of money

I agree with the above post that the period of compounding should be provided, but assuming that the money was compounded annually we can solve it the following way

CI for 2 years = SI for the first year + SI for the 2 nd year on (P + SI of the first year)

5050 = s + 1.02 s

s =2500.

if this were the SI for the first year then the original principle = 125000 Rs considering 2 % interest

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pm
Location: Milpitas, CA
Thanked: 1854 times
Followed by:523 members
GMAT Score:770

by Anurag@Gurome » Mon Feb 21, 2011 8:31 pm
Solution:
Since nothing has been mentioned, we assume that the interest is being compounded annually.
Let the original amount of money be p.
Interest is 2%.
So, the amount after 2 years is p[1 + 2/100]^2 = p[1.02]^2.
The interest will be p[1.02]^2 - p.
Or p[1.02]^2 - p = 5050.
Or p = 5050/[1.02^2 - 1] = 5050/{[1.02+1][1.02 - 1]} = 5050/{2.02*0.02} = 125000.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/