Question

Find the rate at which a sum of money will double itself in 3 years, if the interest is
compounded annually.

Answer 1

Let the Principal be 1
So, Amount is double, amount is 2
Time is 3 yrs
ATQ
A = P(1+r/100)^n

now put values in the formula..

2 = 1(1+r/100)^3
√2 = 1 (1+r/100).........cuberoot of 2
1.26 = 1 + r /100......... multiply 1 to bracket .
1.26 - 1 = r/100
0.26 = r /100
0.26 × 100 = r
26 = r

hence, the rate of interest is 26%.

Hope it helps you.
mark brainiest .