# The difference between the compound interest and simple interest on a certain sum at 10%

The difference between the compound interest and simple interest on a certain sum at 10%

per annum for 2 years is Rs. 631. The sum is

(1) Rs. 63,000

(2) Rs. 63,100

(3) Rs. 63,500

(4) Rs. 63,600

**Answer: (2) Rs.63,100**

**Solution:-**

Let the sum be Rs.X

The difference between compound interest and simple interest = Rs.631

Time = 2 years and Rate of Interest = 10%

Then, [X (10/100 + 1)^{2} – X] – X x 10 x 2/100 = 631

(121 X/100 – X) – 20 X/100 = 631

21 X/100 – 20 X/100 = 631

X = 631 x 100

X = 63,100

Then, the sum is Rs.63,100.

Hence, the correct answer is option (2) Rs.63,100.