A school trip has 240 Primary 5 pupils and 360 Primary 6 pupils.
- Write the ratio of the number of Primary 5 pupils to the number of Primary 6 pupils in its simplest form.
- On another trip, the ratio of the number of Primary 5 pupils to the number of Primary 6 pupils is the same as in part (a). If there are 36 Primary 5 pupils, how many Primary 6 pupils are there?
Need a hint?
In part (a), find the largest number that divides both 240 and 360. In part (b), find how many pupils one part of the ratio stands for.
Worked answer
- (a) Divide both 240 and 360 by 120 to get 2 and 3.
- (a) The simplest form is 2 : 3.
- (b) 2 parts = 36 pupils, so 1 part = 36 ÷ 2 = 18 pupils.
- (b) Primary 6 pupils = 3 parts = 3 × 18 = 54 pupils.
The mistake this question tests
Simplest form in final fraction answers
Leaving the ratio as 240 : 360, or dividing by only 10 to get 24 : 36, is not in simplest form because both terms still share a common factor.
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See the answer →Practise PSLE ratio until the mistakes stop.
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