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Example 8: Convert each of the following percentages into a ratio:

(a) 18% (b) 0.25% (c) 4.6% (d) 280%
Solution: We have,
18 9
(a) 18% = = = 9 : 50
100 50
25 25 1
(b) 0.25% = % = = = 1 : 400
100 100 100 400
×
46 46 23
(c) 4.6% = % = = = 23 : 500
10 100 10 500
×
280 14
(d) 280% = = = 14 : 5
100 5

Practice Time 10A

1. Convert the following fractions into percentages:
45 8 29 3 2
(a) (b) (c) (d) 1 (e) 12
100 15 200 4 5
2. Convert the following percentages into fractions:
2 1
(a) 84% (b) 140% (c) 0.007% (d) 5 3 % (e) 4 8 %
3. Convert the following decimals into percentages:

(a) 6.98 (b) 0.42 (c) 1.67 (d) 0.003 (e) 23.9
4. Convert the following percentages into decimals:

1
(a) 27% (b) 148% (c) 2.54% (d) 0.07% (e) 6 %
5
5. Convert the following ratios into percentages:
(a) 12 : 35 (b) 77 : 100 (c) 58 : 78 (d) 9 : 4 (e) 28 : 15

6. Convert the following percentages into ratios:
(a) 57% (b) 125% (c) 4.8% (d) 0.19% (e) 0.008%

Parts Always Add to Give a Whole

All parts of a quantity or a number are added together to form a whole or 100%.

So, if we are given one part, we can always find out the

other part.
Suppose there are 60% girls in your class, that means Quick Check
there are 100 students, then 60 out of 100 are girls and the 1. 35% + _______% = 100%

remaining would be boys. 2. 64% + 20% +________ % = 100%
3. 45% = 100% – _________ %
Thus, there would be (100 – 60)% = 40% boys in the class. 4. 70% = ______% – 30%

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