In a certain duration of time, a sum become 2 times itself at the rate of 5% per annum simple interest. What will be the rate of interest if the same sum becomes 5 times itself in the same duration?

Correct option is A

Given:

Sum becomes 2 times at 5% p.a rate 

At same time time the same sum becomes 5 times.

Formula  used:

​$$S.I = \frac{P × R × T}{100}$$​​

Solution:

According to question,

​$$\frac{P × 5 × T}{100} = P$$​​

=> T = 20 years

Now, $$\frac{P × R × T}{100} = 4P$$​​

=> $$\frac{P × R × 20}{100} = 4P$$​​

=> R = 4 × 5 = 20%

Hence, The Required value is 20%.