In how many years will a sum of money double itself at 18.75 % p.a simple interest?

5 years 4 months

A sum of money will double itself means, P = 100 and Amount = 200 that means Interest = 100

Simple interest =  \(\frac{\text{P x R x T} }{ 100}\)

100 =  \(\frac{\text{100 x 18.75 x T} }{ 100}\)

10000 = T x 1875

T = \(\frac{ 10000}{1875 }\)

T = \(\frac{ 16}{3 }\)

T =  5 \(\frac{ 1}{3 }\)

Thus, 5 years 4 months is correct answer.