# What will be the Sum and Rate of Interest? If

A certain sum at a certain rate of simple interest amounts to Rs.1200 in 4 years and Rs.1450 in 9 years. Find the sum and rate of interest:

- Rs. 500, 10%
- Rs. 800, 8%
- Rs. 900, 7%
- Rs. 1000, 5%

**Answer: (4) Rs.1000, 5 %**

**Explanation:-**

Let the certain amount be Rs.X

The amounts to Rs.1200 in 4 years and Rs.1450 in 9 years.

The simple interest of 5 years = 1450 – 1200

= Rs.250

Therefore, simple interest of four years = 250 x 4/5

= Rs. 200

Principal = 1200 – 1000

= Rs.1000

**Formula-**

**Simple Interest = P x R x T/100**

**Where, P = principal , R = rate, & T = time.**

Then, 200 = 1000 x 4 x R/100

200 = 40 R

R = 200/40

R = 5 %.

Then, the certain amount is Rs.1000 & the rate is 5 %.

Hence, the answer is (4) Rs.1000, 5 %.