Question

At what rate per cent per annum simple interest will a sum double itself in 10 year *​

Answer 1

Answer :-

Given :-

• Time = 10 years
• Amount = 2 × sum

To Find :-

• Rate of interest

Solution :-

Let the sum be x

Amount = 2 × x = 2x

→ Simple interest = Amount - Sum

→ SI = 2x - x

→ SI = x

Now, we have :-

• Simple interest = Rs. x
• Sum = Rs. x
• Time = 10 years

Substituting the value in formula :-

→ SI = P × R × T / 100

→ x = x × 10 × R / 100

→ x = 10xR / 100

→ x = xR/10

→ 10x = xR

→ R = 10x / x

→ R = 10

Rate of interest = 10% p.a.