Question

The simple interest on a certain sum for 2.5 years at 12 per cent per annum is ₹ 300 less than the simple interest on the same sum for 4.5 years at 8 per cent per annum. Find the sum.

Answer 1

Let the sum be ₹ P.

Interest for 2.5 years at 12% per annum

= `(P xx 12 xx 2.5)/100`

= `3/10 P`

Interest for 4.5 years at 8% per annum

= `P xx 8/100 xx 4.5` 

= `9/25 P`

According to question,

`3/10 P = 9/25 P - 300`

⇒ `(9/25 - 3/10) P = 300`

⇒ `((36 - 30))/100 P = 300`

⇒ `6/100 P = 300`

⇒ `P = (300 xx 100)/6 = 5000`