Page 125 - Maths Skills - 8

Comparing Quantities 123

Example 2: What will be the amount on ` 10020 for 2 years when the interest is compounded annually at the
rate of 10% per annum for the first year and 15% for the second year.
Solution: Given: P = ` 10020 n = 2 years R = 10% R = 15% A = ?
1 2
Amount (A) after 2 years
R R 10 15
= P 1 1 1 2 = ` 10020 1 1

100 100 100 100
110 115
= ` 10020 = ` 10020 (1.10) (1.15) = ` 12675.30.
100 100

Example 3: Find the compound interest on ` 12000 at 20% per annum for 2 1 years.
4
Solution: Given: P = ` 12000 R = 20%
1 x 1
T = 2 years, here n = 2 and = A = ?
4 y 4
x R 1 20

n

1
Amount (A) after 2 years = P 1 R 1 y = ` 12000 1 20 2 1 4

4 100 100 100 100

2
120 105 12 12 21
= ` 12000 = ` 12000 = ` 18144
100 100 10 10 20
Compound interest = ` (18144 – 12000) = ` 6144.
Exercise 8.5

1. By using formula, find out the amount and the compound interest.

(i) Principal = ` 24000, Rate = 5% per annum, Time = 3 years.
(ii) Principal = ` 8000, Rate = 12% per annum, Time = 2 years.
1
(iii) Principal = ` 18000, Rate = 10% per annum, Time = 3 years.
2
2. Shyam purchased a car for ` 180000 by taking a loan from a bank. If the bank takes interest 10% for
the first year and 12% for the second year, then find the total compound interest paid by him to the
bank at the end of the second year.
3. Find the compound interest on ` 46875 at 8% per annum for 2 1 years.
2
4. Manohar borrowed ` 10000 from his friend 2 years ago. If his friend takes 8% per annum compound
interest, then find the interest on the principal.
5. Find the amount and the compound interest on ` 24500 for 3 years, compounded annually, rate of
interest being 5%, 8% and 10% per annum for the first, second and third year respectively.
6. Find the amount and the compound interest on ` 18000 for 2 years, compounded annually, the rate of
interest being 8% for first year and 12% for second year.
1
7. Ram deposited ` 781250 in a bank for 3 years. If the bank pays 8% per annum compound interest,
2
then find the total amount he received.