Back to: Mathematics Primary 6
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Percentages are used to indicate fractions. When a fraction is written with 100 as the denominator it is called a percentage. It has the symbol %. So, 25% means 25 out of every 100.
Percentages often indicate proportions. For example, labels in clothes indicate proportions of different yarns in the fabric. 100% is the same as the whole, or one hundred per hundred.
40/100 (or 0.4) is polyester.
- A building society offers 90% mortgages to first-time buyers. How much would the Smiths get on a house valued at N150,000?
They want to find 90% of N150 000. 90% =90/100 = 0.9.
0.9 × 150 000 = 135, 000
So, the Smiths would get N135,000
- Express each of the following percentages as fractions:
- (a) 40%
- (b) 8%
- (c) 70%
- (d) 5 1/2%
- Express each of the following percentages as decimals:
- (a) 50%
- (b) 85%
- (c) 7%
- (d) 7 1/2%
Converting to a percentage
Fe converted to percentages, by multiplying by 100%.
So, for example, 0.17, 0.3 and can be expressed as percentages as follows:
0.17 × 100% = 17%;
0.3 × 100% = 30%;
Decimals or fractions bigger than 1 correspond to percentages greater than 100%. For example,
= 1.75, which as a percentage is 1.75 × 100% = 175%.
- Convert each of the following to percentages. Round off the percentages to whole numbers.
- (i) 0.8
- (ii) 0.21
- (iii) 0.70
- (iv) 2.4
(b) (i) 1/2 (ii) 1/8 (iii) 1/9 (iv) 1 1/7
- Express each of the following percent as a ratio:
(i) 12 % (ii) 11/2 % (iii) 4/5 % (iv) 6.5 % (v) 0.28%
- Convert each of the following percent as ratio:
(i) 25 % (ii) 115 % (iii) 62/5 % (iv) 0.8 % (v) 6.72 %
Word Problem on Percentages
Example: In a basket of apples, 12% of them are rotten and 66 are in good condition. Find the total number of apples in the basket.
Let the total number of apples in the basket be m
12 % of the apples are rotten, and apples in good condition are 66
Therefore, according to the question,
88% of m = 66
88/100 × m = 66
m = (66 × 100)/88
m = 3 × 25
m = 75. Therefore, total number of apples in the basket is 75.
- In an examination, 300 students appeared. Out of these students; 28 % got first division, 54 % got second division and the remaining just passed. Assuming that no student failed; find the number of students who just passed.
- An alloy contains 26 % of copper. What quantity of alloy is required to get 260 g of copper?
- In an exam Ashley secured 332 marks. If she secured 83 % makes, find the maximum marks.
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