Question

In the following table, the principal, period and rate of interest are given. Find the interest in each case.

Sr. No.	Principal (Rs)	Period (years)	Rate of interest (p.c.p.a.)
1. 2. 3. 4. 5.	400 1,500 15,000 20,000 3,500	5 3 4 2 6	6 4 8 10 5

Answer 1

Formula for calculating interest:

$\mathrm{Interest}=\frac{\mathrm{Principal}\times \mathrm{Rate}\mathrm{of}\mathrm{interest}\left(\mathrm{p}.\mathrm{c}.\mathrm{p}.\mathrm{a}.\right)\times \mathrm{Time}\left(\mathrm{in}\mathrm{years}\right)}{100}$

(1) Principal = Rs 400
Rate of interest = 6 p.c.p.a.
Time = 5 years
Using the above formula, we get:
Interest$=\frac{400\times 6\times 5}{100}=\frac{12000}{100}=120$

Thus, the interest is Rs 120.

(2) Principal = Rs 1500
Rate of interest = 4 p.c.p.a.
Time = 3 years
Using the above formula, we get:
Interest$=\frac{1500\times 4\times 3}{100}=\frac{18000}{100}=180$

Thus, the interest is Rs 180.

(3) Principal = Rs 15000
Rate of interest = 8 p.c.p.a.
Time = 4 years
Using the above formula, we get:
Interest$=\frac{15000\times 8\times 4}{100}=\frac{480000}{100}=4800$

Thus, the interest is Rs 4800.

(4) Principal = Rs 20000
Rate of interest = 10 p.c.p.a.
Time = 2 years
Using the above formula, we get:
Interest$=\frac{20000\times 10\times 2}{100}=\frac{400000}{100}=4000$

Thus, the interest is Rs 4000.

(5) Principal = Rs 3500
Rate of interest = 5 p.c.p.a.
Time = 6 years
Using the above formula, we get:
Interest$=\frac{3500\times 5\times 6}{100}=\frac{105000}{100}=1050$

Thus, the interest is Rs 1050.