Page 186 - ICSE Math 5

3. Convert the following fractions to percentages.
3 9 11 7 12
(a) (b) (c) (d) (e)
5 10 20 8 15
4. Convert the following percentages to fractions.
1 1
(a) 36% (b) 52% (c) 20 % (d) 1 % (e) 74%
2 8
5. Convert the following decimals to percentages.

(a) 0.8 (b) 4.09 (c) 2.708 (d) 0.437 (e) 6.75

6. Convert the following percentages to decimals.
(a) 19% (b) 43.2% (c) 88% (d) 114% (e) 42.5%

Finding Percentage of a Given Number or a Quantity

To find the percentage of a given number or a quantity, we express the percentage as a fraction
and ‘of’ as the sign of multiplication. Then we multiply the fraction with the given quantity.

Example 6: Find 4% of 16. Mental Maths
4 4 × 16 64
Solution: 4% of 16 = × 16 = = = 0.64 Select the correct answer.
100 100 100
(a) 1% of 2 is _______.
1
Example 7: Find 6 % of 200 km. (i) 0.02 (ii) 0.2
2
(iii) 1.2 (iv) 0.002
1 13 1 13
Solution: 6 % = × =
2 2 100 200 (b) 100% of 200 is _______.
(i) 300 (ii) 200
1 13 1
 6 % of 200 km = × 200 km = 13 km (iii) 100 (iv) 400
2 200
1
On the other hand, if two numbers are given and one of the numbers is to be expressed as
percentage of another number, we divide the given number whose percentage is to be found by
the total number and then multiply the result by 100 followed by the per cent sign.

Example 8: In a bouquet, there are 60 red roses and 20 white roses. Find the percentage of red
roses in the bouquet.
Solution: Total number of roses in the bouquet = 60 + 20 = 80
Number of red roses = 60
3 60 25
 Percentage of red roses = × 100 % = 3 × 25% = 75%
80
4
So, 75% of roses in the bouquet are red.

Example 9: If 60% of 1,250 students are girls in a school, how many students are boys in the
school?
Solution: Total number of students in the school = 1,250
Number of girls = 60% of 1,250
60
= × 1250 = 6 × 125 = 750
100

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