The ratio between principal to amount is 4 : 5 for certain time and on certain rate of simple interest. After three years that ratio becomes 5 : 7. Find rate of interest. |
04% 05% 08% 10% |
05% |
Principal : Amount Original ⇒ 4 : 5 ..............(i) After 3 yrs. ⇒ 5 : 7 ..............(ii) In the case of S.I., principal is always remains same, therefore, to make the principal equal: (i) × 5 and (ii) × 4
Principal : Amount Original ⇒ 20 : 25 After 3 yrs. ⇒ 20 : 28 We can see, Amount increased by 3R in 3 years, it means S.I. received in 3 years is 3R, Therefore, S.I. in one year = 1R Principal = 20R0 Rate of Interest = \(\frac{1}{20}\) × 100% = 5% pa |