# The difference between the compound Interest and simple interest :

The difference between the compound Interest and simple interest on a certain sum at 10% per annum for 2 years is Rs. 631. Determine the sum:

- Rs. 70000
- Rs. 61000
- Rs. 62000
- Rs. 63100

**Answer: (4) Rs. 63100**

**Solution:-**

Let the sum be Rs. X

The difference between the compound interest and simple interest on a certain sum at 10% per annum for 2 years is Rs. 631.

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

{X x 11 x 11/10 x 10 – X} – X/5 = 631

(121 X – 100 X)/100 – X/5 = 631

(21 X – 20 X)/100 = 631

X = 631 x 100

X = 63100

Then, sum will be Rs. 631000.

Hence, the correct answer is option (4) Rs. 63100.