At what rate of interest (in percentage) per year will a sum of money double itself in 4 years on simple interest?

Correct option is A

Given:

Time t = 4 years

Amount doubles on Simple Interest: A = 2P

Formula Used:

Simple Interest amount: A = P(1+rt)

Solution: 

For doubling: 2P = P(1+rt)

rt = 1

r $$=\dfrac{1}{t}$$​​

r$$=\frac{1}{4}=0.25$$​= 25% per annum