Problem Solving

I came across this one doing gmatprep yesterday, it was one of my 4 mistakes in quant. But i was 100% sure that i solved it right.

Problem: If 10000 principal has to be invested at a simple percent x for n years, which of the forrowing represents INTEREST gained by the investment.

1) 10000(x/100)^n
2) 10000n(x/100)
3) 10000(1+x/100)^n
4) 10000n(1+x/100)
5) whatever

I ll post the OA after few replies. [/spoiler]

IMO 2

wats the OA

Well, khm, i am blamed, just figured it out
I don't know why, but i thought that compounded and simple rates differ only when we count interest quaterly or semi-annually
Xcusemeplz, you are right. OA is B.
Compounded would be A
Simple is B.

NikolayZ wrote:Well, khm, i am blamed, just figured it out
I don't know why, but i thought that compounded and simple rates differ only when we count interest quaterly or semi-annually
Xcusemeplz, you are right. OA is B.
Compounded would be ASimple is B.

i think u r again mistaken as compounded IMO will be C

Ci=P[1+r/100]^t
si=prt/100
ci quarterly =p[1+r/400]^4t
ci half yearly=p[1+r/200]^2t

just check again i may be wrng

no mate, C and D represent interest + principal. Question asked only about interest gained. So, b for simple.
Compounded interest gain formula is nicely posted by Acenikk

Hi NikolayZ, you are right that the answer is 2, but you are perhaps wrong on the compound interest part. The CI should be 10000(1 + x/100)^n - 10000. How can this be 10000(x/100)^n ?

Argh, i should stop learning for the last day before exam
You are right. Thanks.
p.s. corrected previous message.