# The compound interest on Rs.12000 for 9 months at 20% per annum :

The compound interest on Rs.12000 for 9 months at 20% per annum, interest being compounded quarterly is:

- Rs.2089.70
- Rs.1750
- Rs.2136.40
- Rs.1891.50

**Answer: (4) Rs. 1891.50**

**Explanation:-**

**Given-**

Principal = Rs. 12, 000, Time = 9 months & rate = 20% per quarterly.

**Formula- Compound Interest = P [(1 + R/100)^{t} – 1] Where, P = principal, R = rate, t = time.**

Then, Compound interest = 12, 000 [(1 + 20/4 x 100)³ – 1] { If rate of compound interest quarterly, time becomes 4 times and rate of interest 1/4 time}

= 12, 000 [(1 +1/20)³ – 1]

= 12, 000 [(21/20)³ – 1]

= 12, 000 x 21 x 21 x 21/20 x 20 x 20 – 12, 000

= 3 x 9261/2 – 12, 000

= 13891.5 – 12, 000

= Rs. 1891.5

Hence, the answer is (4) Rs. 1891.50.