MAT Exam 2022 Paper

Concept:This problem uses Simple Interest calculations at two different time periods.Explanation:Interest that would be received after 5 years at $10\%$ per annum:$$\text{SI}_{5} = \frac{24000 \times 5 \times 10}{100} = \text{Rs. }12,000$$Interest actually received after 3 years is Rs. $6,640$ less than this:$$\text{SI}_{3} = 12,000 - 6,640 = \text{Rs. }5,360$$Let the actual rate allowed by the bank be $R\%$ per annum.Using simple interest formula for 3 years:$$5,360 = \frac{24000 \times R \times 3}{100}$$$$5,360 = 720R$$$$R = \frac{5360}{720} = 7.44\%$$Answer:The rate of interest allowed by the bank is $7.44\%$, i.e. Option B.