Page 86 - ICSE Math 8

Example 6: A person deposits ` 15,000 in a bank and gets 10% of the amount as interest at the end of the
year. How much money will he have in his bank account after 2 years?
Solution: Money deposited = ` 15,000
Interest earned at the end of 1st year = 10% of ` 15,000
10
= 100 × ` 15,000 = ` 1,500

∴ Total money in bank after 1 year = ` (15,000 + 1,500) = ` 16,500
10
Interest earned at the end of 2nd year = 10% of ` 16,500 = 100 × ` 16,500 = ` 1,650

∴ Total money in bank after 2 years = ` (16,500 + 1,650) = ` 18,150
Example 7: The circumference of a circular park is 200 km. It is Maths Info
measured wrongly as 240 km. Find the percentage
error. Percentage error = Error × 100%
Solution: Error = 240 km – 200 km = 40 km Actual value
Error 40
∴ Percentage error = Actual value × 100% = 200 × 100% = 20%

EXERCISE 7.1

1. Evaluate the following.
(a) 45% of 160 – 32% of 50 + 28% of 75 (b) 2.7% of 450 + 3.6% of 220 + 4.9% of 760
2. Determine the following.
(a) 3.8% of 1,450 (b) 27% of 800
3. Mr Gupta earns ` 6,25,400 per annum. He spends 69% of it and saves the rest. How much money does
he save per annum?
4. A tank can store 10 thousand litres of water. Due to a hole in the tank, 11.5% water has leaked. How
much water is left in the tank?
5. In an election, candidate A got 66% of the total votes and won the election by 36,000 votes. How many
votes were polled in all?
6. The cost of a car depreciates every year by 25% of its cost at the beginning of the year. If the present cost
of the car is ` 2,65,000, find its cost:
(a) after 1 year (b) after 2 years
7. A number 4.745 is wrongly read as 4.475. Find the percentage error.

8. In an election, a candidate got 43% of the total votes and lost the election by 28,392 votes. Find the total
votes polled and the number of votes of the winning candidate.
9. In annual examinations, Rahul scored 68 marks and failed by 13 marks. If the pass percentage was 45%,
find the maximum marks.
10. 56% of a number is 154. Find the number.
11. A person has to pay 7% of his income as tax. If he pays ` 1,596 as tax, find his salary.
12. If 8 L of water is poured in 192 L milk, what is the percentage of each in the mixture?

Increase or Decrease in Percentage
To find an increase or decrease of a quantity in percentage, we first find the increase or decrease in its value,
divide it by the original value and then multiply by 100% to get the required percentage.

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