The simple interest on a sum of money is 3/5 of the principal in 12 years. What is the rate of interest per annum?

Correct option is C

Given:

Simple Interest (SI) = $$\frac{3}{5}$$​ of the principal (P)

Time(T) = 12 years

Formula used:

​$$SI= \frac{P\times R\times T}{100}$$

Solution:

SI = $$\frac{3}{5}P$$

​​$$\frac{3}{5}P$$= $$\frac{P\times R\times 12}{100}$$

​​$$\frac{3}{5}$$$$=\frac{ R\times 12}{100}$$

3×100 = 5×12R

300 = 60R

R= $$\frac{300}{60}$$

R= 5

Rate of interest per annum is 5%.

Thus, correct option is (c)