# At what simple rate of interest a sum is double in 8 years ?

(a) 11.0%

(b) 12.5%

(c) 12%

(d) 13.5%

**Answer: (b) 12.5%**

**Solution:-**

Let the rate be R% and principal be Rs. X

Sum is double in 8 years,

Then, X = X x R x 8/100

R = 100/8

R = 25/2

R = 12.5%

Then, Rate of simple interest 12.5% a sum is doubled in 8 years.

Hence, the correct answer is option (b) 12.5%