Advertisement

### Question

The compound interest on a certain sum of money at 5% for a period of 2 years is Rs. 3075. What is the SI on this sum if the rate is halved, and time doubled?

**A**

Rs. 3000.

**B**

Rs. 3100.

**C**

Rs. 2900.

**D**

Rs. 3200.

**Soln.**

**Ans: a**

The shortcut formula is CI = Pr(r + 200)/10000. Putting CI = 3075, r = 5, we get 3075 = ${P × 5 × (5 + 200)}/10000$. We can solve it to get P = Rs. 30000. The SI = P × (2 × t) × (r / 200) = P × t × (r / 100). Putting t = 2, r = 5 and P = 30000, we get SI = Rs. 3000.