The difference between the simple interest recovered from two different sources on ₹1,200 for 3 years is ₹10.80. The difference between their rates of interest is:

Correct option is C

Given:

Principal amount (P) = ₹1,200

Time (T) = 3 years

Difference in simple interest (SI) = ₹10.80

Formula used:

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

Solution:

Let the two rates of interest be $$R_1$$% and $$R_2$$%

​$$SI_1$$ = $$\frac{1200 \times R_1\times 3}{100}$$ 

$$SI_2$$ = $$\frac{1200 \times R_2\times 3}{100}$$ 

The difference in simple interest is ₹10.80: 

​$$SI_1 - SI_2$$ = 10.80

​$$\frac{1200 \times R_1\times 3}{100}$$ - $$\frac{1200 \times R_2\times 3}{100}$$ = 10.80

$$36 \times R_1 - 36 \times R_2$$ = 10.80

$$36(R_1-R_2)$$ = 10.80

$$R_1-R_2 =$$ $$\frac{10.80}{36}$$ 

$$R_1-R_2$$ = 0.3

​The difference between their rates of interest is 0.3%​