Question

In a class, 12 pupils walk to school. This is 40% of the pupils in the class. How many pupils are there in the class?

Answer 1

The way i would approach this problem is using proportions
$\frac{12}{x} * \frac{40}{100}$                (cross multiply and you get:)
40x = 1, 200        (divide both sides by 40)
x = 30

So there are 30 students in the class

Answer 2

40% = 12

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Find 1% :
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40% = 12
1% = 12 ÷ 40 
1% = 0.3

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Find 100% :
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1% = 0.3
100% = 0.3 x 100
100% = 30

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Answer: There are 30 pupils in the class.
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