# What is the sum?

If the difference between simple interest and compound interest on a certain sum of money for 3 yrs at 10% p.a. is Rs. 15.50.The sum is:

- Rs. 100
- RS. 500
- Rs. 1500
- Rs. 2000

**Answer: (4) Rs. 2000**

**Explanation:-**

Let the sum to be found be X

Rate of interest (r)= 5% p.a.

Time(t) = 3 yrs

C.I – S.I = ₹ 15.25

X[(1+r/100)^3 -1-(5 x 3)/100]=₹15.25

Putting the values of r and t in the above expression and solving it, we get:

X= ₹15.25 x (8000/61)

Thus, X = ₹2000.

Hence, the correct answer is option (4) Rs. 2000