A toy shop has 108 red kites and 84 blue kites. What is the ratio of the number of red kites to the number of blue kites in its simplest form?
- 27 : 21
- 9 : 7
- 7 : 9
- 36 : 28
Need a hint?
Look for one number that divides both 108 and 84 exactly, and keep dividing until no common factor is left.
Worked answer
- Find the highest common factor of 108 and 84, which is 12.
- Divide 108 by 12 to get 9.
- Divide 84 by 12 to get 7.
- The ratio in simplest form is 9 : 7.
The mistake this question tests
Simplest form in final fraction answers
Pupils divide only by a small common factor such as 4 or 3, getting 27 : 21 or 36 : 28, and stop there without checking whether the ratio can still be simplified.
How to fix it at home →More PSLE ratio questions
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See the answer →Practise PSLE ratio until the mistakes stop.
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