A zoo had 90 more visitors on Sunday than on Saturday. 35 of the visitors on Saturday and 110 of the visitors on Sunday were children. The number of adults over the two days was 4 times the number of children over the two days.
- How many visitors were there on Saturday? [2]
- How many adults visited the zoo on Sunday? [2]
Need a hint?
If adults are 4 times the children, what fraction of all the visitors are children? Compare that fraction with 35 of Saturday and 110 of Sunday.
Worked answer
- (a) Adults were 4 times the children, so children were 1 out of 5 equal parts of all the visitors: 15 of the total.
- So 35 of Saturday + 110 of Sunday = 15 of Saturday + 15 of Sunday.
- Take away 15 of Saturday and 110 of Sunday from both sides: 25 of Saturday = 110 of Sunday.
- 25 = 410, so 410 of Saturday = 110 of Sunday. Sunday is 4 times Saturday.
- Let Saturday be 1 unit and Sunday 4 units. The difference is 3 units = 90, so 1 unit = 30. Saturday had 30 visitors.
- (b) Sunday visitors = 4 × 30 = 120.
- Children on Sunday = 110 of 120 = 12.
- Adults on Sunday = 120 − 12 = 108.
The mistake this question tests
Stopped at one part in ratio
Many pupils work out only the Sunday children (12) and stop, or they use 15 of Sunday instead of 110 because they forget that each day has its own fraction of children.
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See the answer →Practise PSLE fractions until the mistakes stop.
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