XAT 2015QA & DI Question 12

Compound InterestEasy

In the beginning of the year 2004, a person invests some amount in a bank. In the beginning of 2007, the accumulated interest is Rs. 10,000 and in the beginning of 2010, the accumulated interest becomes Rs. 25,000. The interest rate is compounded annually and the annual interest rate is fixed. The principal amount is:

Answer & solution

  • A

    Rs. 16,000

  • B

    Rs. 18,000

  • Rs. 20,000

  • D

    Rs. 25,000

  • E

    None of the above

Solution

Let P be the principal.

By the given conditions,

P×(1+r100)3-P=10000

​​​​​​​P×(1+r100)6-P=25000​​​​​​​​​​​​​​

Let  â€‹â€‹â€‹â€‹â€‹â€‹â€‹(1+r100)3=X

Thus,

P(X - 1) = 10000             ...(i)

P(X2 - 1) = 25000           ...(ii)

Dividing (ii) by (i),

X + 1 = 5/2

∴ X = 3/2

Substituting value of X in (i), we get

P = Rs. 20,000

Hence, option (c).

XAT 2015 QA & DI Q12: In the beginning of the year 2004, a person invests some amount in a bank. In the beginning of 2007, the accum — Solution | TheCATExam