Question

P took Rs. 15000 loan at a certain rate of simple interest per annum and Rs. 9000 at 1% more. After three years he paid Rs. 3150 as simple interest. Find at what rate did he take Rs. 9000 loan?
1. 5%
2. 6%
3. 4%
4. 8%

Answer 1

Correct Answer - Option 1 : 5%

Given:

Principal (P₁) = Rs. 15000, Principal (P2) = Rs. 9000

Total Interest = Rs. 3150, Time (T) = 3 years 

Formula used:

S.I. = (P × R × T)/100

Where, S.I. → Simple Interest

P → Principal

R → Rate 

T → Time

Calculations:

Let the rate of interest charged on P₁ be R.

According to the question,

\(\Rightarrow \frac{15000\ \times\ 3\ \times\ R}{100}\ + \ \frac{9000\ \times\ (R\ +\ 1)\ \times 3}{100}\ = \ 3150\)

⇒ 450R + 270(R + 1) = 3150

⇒ 450R + 270R + 270 = 3150

⇒ 720R = 2880

⇒ R = 4%

The rate charged on Rs. 9000 = 4% + 1% = 5%

∴ The Rate charged on Rs.9000 is 5%.