836 students — who takes the bus
There are 836 students in a school. of the boys and of the girls take bus to school. The number of boys who do not take bus is twice the number of girls who do not take bus. How many girls do not take bus?
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The pattern behind it: The equal concept
The question tells you a part of one pile equals a part of another.
In this one. Make the two numerators the same, and the fraction equation turns into a ratio of the two wholes: 3/10 of boys = 3/12 of girls says one tenth of the boys equals one twelfth of the girls, so Boys : Girls = 10 : 12.
How to spot it
Two different groups each get their own fraction or percentage, and the question links them with 'the same as', 'twice as many as', or a shared cost across different units.
Common mistake
Children compare the two fractions without first relating them to a common whole. A smaller fraction of a larger group can be bigger than a larger fraction of a smaller group.
Try one like it
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All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
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