Correct Answer - Option 3 : 50%
Given:
A sum of money becomes 11 times of principal
Time = 20 years
Formula Used:
Simple Interest = Amount - Principal
Simple Interest = (Principal × Rate × Time)/100
Calculation:
Let the Principal be P
Then Amount after 20 years will be 11P
Simple Interest = 11P - P = 10P
10P = (P × Rate × 20)/100
⇒ Rate = 50%
∴ The Rate of interest per annum is 50%