Question

Arun lent ₹ 5,000 to Balaji for 2 years and ₹ 3,000 to Charles for 4 years on simple interest at the same rate of interest and received ₹ 2,200 in all from both of them as interest. Find the rate of interest per year

Answer 1

Principal lent to Balaji P₁ = ₹ 5000

Time n₁ = 2 years

Let r be the rate of interest per year

Simple interest got from Balaji = `"Pnr"/100`

⇒ I₁ = `(5000 xx 2 xx "r")/100`

Again principal let to Charles P₂ = ₹ 3000

Time (n₂) = 4 years

Simple interest got from Charles (I₂) = `(3000 xx 4  xx "r")/100`

Altogether Arun got ₹ 2200 as interest.

∴ I₁ + I₂ = 2200

`(5000 xx 2 xx "r")/100 + (3000 xx 4 xx "r")/100` = 2200

100r + 120r = 2200

220r = 2200

r = `2200/220`

r = 10%

Rate of interest per year = 10%