Question

A sum of money doubles in 10 years in how many years it triples at the same rate of simple interest

Answer 1

let the sum be x

then after 10 years

sum = x, amount = 2x, time = 10 years

SI = Amount - sum

SI = 2x - x = x

SI = x

SI = PRT / 100

x = x × R × 10 / 100

10x / x = R

R = 10 %

Now we have to find the time span in which sum becomes thrice of itself

sum = x, amount = 3x, R = 10 %

SI = amount - sum

SI = 3x - x = 2x

SI = PRT / 100

2x = x × 10 × T / 100

10 × 2x/x = T

T = 10× 2 = 20 years

Hence your answer is 20 years

hope it explains you