Page 113 - Math Skill - 5

Percentage, Profit and Loss 111

Example 4: What per cent is 3 mm of 1 cm?

Solution: 3 mm out of 1 cm
Fact-o-meter
1 cm = 10 mm In fraction, the units of
3 numerator and denominator
Given fraction =
10 must be same.
3
Thus, required % = × 100% = 30%
10

Exercise 8.3

1. Find the value.

(a) 16% of 550 (b) 20% of 66 (c) 50% of 61 (d) 20% of 64
2. Find the value.

(a) 29% of 436 kg (b) 83.6% of 42 m (c) 70% of 190 km
(d) 10% of 180 cm (e) 95% of 170 L (f) 60% of 90 g

3. Find the answer.
(a) What per cent of ` 1 is 60 p? (b) What per cent is 225 mg of 2.5 g?

4. Find the length whose 50% is 250 m.
5. Find the rupees whose 12% is ` 15.

Word Problems

Let’s Attempt

Example 1: In a class of 40 pupils, 45% are girls. How many girls are there in the class? How
many boys are there?
Solution: Percentage of girls = 45%

Total pupils = 40
9
2
Number of girls = 45% of 40 = 45 × 40 = 18
100
5
Number of boys = 40 – 18 = 22
Hence, there are 22 boys and 18 girls.

Example 2: Rekha had ` 250. She spent 30% of it on a cinema ticket. How much did the
ticket cost?

30
Solution: Cost of the ticket = 30% of ` 250 = × ` 250 = ` 75
100

Hence, the cost of the ticket is ` 75.