Page 129 - Maths Skills - 8

Comparing Quantities 127

Example 4: A computer costs ` 70000. It depreciates at the rate of 5% and 10% during the first year and
second year respectively. Find its depreciated value after 2 years.

Solution: Given: Here, initial value (P) = ` 70000 R = 5%; R = 10%
2
1
The value after 2 years (A)
R R 5 10 95 90
A = P 1 1 1 2 = ` 70000 1 1 = ` 70000 × × = ` 59850

100 100 100 100 100 100
Hence, the depreciated value of the computer after 2 years is ` 59850.

Exercise 8.7

1. The present population of a town is 30000. If the rate of growth is 10% every year, find the population
after 2 years.

2. The population of a town is 10000 in a certain year. If the rate of growth is 8% per annum, then find the
total population after 2 years and also find the net increase in population.
3. The distance between the earth and a planet is 1000000 km. If this distance is decreasing by 2.5% every
year, then find the distance between the planet and the earth after 3 years.
4. The number of cycles produced every year by the Hero group is 150000. If 20% increment in production
is noted in the first year and 10% depreciation is noted in the second year, then find the net increment
or decrement in two years.
5. The value of a machine is ` 90000. If it depreciates at the rate of 10% and 15% during the first year and
the second year respectively, find its depreciated value after 2 years.

6. The value of a refrigerator which was purchased 3 years ago, depreciates at 10% per annum. If its
present value is ` 6561, how much was it purchased for?

ASSESSMENT TIME

COMPETENCY BASED QUESTIONS (iii) 6 (iv) 20
A. Multiple-Choice Questions 7 7

5 3. If S.I. = ` 36, R = 3% per annum, T = 3 years,
1. is equal to: then principal is equal to:
4
(i) 80% (ii) 75% (i) ` 600 (ii) ` 400
(iii) 50% (iv) 125% (iii) ` 500 (iv) ` 450
4. The compound interest and the simple interest
2. 35% is equal to: on a certain sum at a certain rate for 1 year are:

7 100 (i) unequal (ii) equal
(i) (ii)
20 35 (iii) both (i) & (ii) (iv) none of these