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PSLE 2023 — Three paint tins
Gopal had 3 identical tins of paint that were filled to the brim. He poured 760 ml out of each tin. The total amount of paint left in the 3 tins was equal to the amount of paint in 1 full tin at first. How much paint was in each tin at first?
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The pattern behind it: Units and parts
Cut one amount into equal shares. One number tells you what a share is worth.
In this one. If 3 tins minus the pourings leaves 1 tin, then what was poured out is exactly the other 2 tins — so 3 × 760 = 2280 ml is 2 whole tins, not a fraction of one.
How to spot it
A single amount is split by a ratio, a fraction or a percentage. One extra number gives you the leftover, the difference, or the value of one share.
Common mistake
Children match the given number to the wrong number of shares, using the whole bar when the number covers only the leftover or the difference between two people's shares.
Try one like it
Standard Class trip savings — four classmates Four classmates saved money for a class trip. Liam saved $15 less than Sara. Priya saved twice as much as Sara. Tom saved $9 less …The 33 problem patterns
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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