Question

Solve:

(1) At a certain rate, the interest on Rs 5000 is Rs 1200 after 4 years. What will be the interest on Rs 15000 in the same time and at the same rate?

(2) The interest for 2 years on Rs 18,000 at a certain rate is Rs 3240. What will be the interest for the same time at the same rate on a principal of Rs 6000?

Answer 1

(1) Interest = Rs 1200
The principal increases by three times (from Rs 5000 to Rs 15000).
Because the time and the rate of interest are the same, the interest also increases by three times.
∴ Interest = Rs 1200 × 3 = Rs 3600

(2) Interest = Rs 3240
The principal decreases by three times (from Rs 18000 to Rs 6000).
Because the time and the rate of interest are the same, the interest also decreases by three times.
∴ Interest$=\frac{\mathrm{Rs}3240}{3}=\mathrm{Rs}1080$