A sum of money doubles in 14 years. In how many years would it triple if the rate of interest is considered as simple?

Correct option is B

A = P(1 + rt)
where, A is the total amount, P is the principal, r is the rate of interest per
year, and  t is the time in years.
According to question,
If the money doubles in 14 years, A = 2P and t = 14.
2P = P(1 + r x 14)
2 = 1 + 14r
14r = 1
r = 1/14 (per year).
For the money to triple, A = 3P.
3P = P(1 + r x t)
3 = 1 + (1/14) x t
(1/14) x t = 2
t = 2 x 14 = 28 years.