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PSLE Math Ratio, Percentage & Rate: Do's & Don'ts
8 Nov 2025·5 min read·The Tutor's Table
Ratio, percentage, and rate show up in almost every PSLE Math paper — usually dressed up in a story. Students who recognise them quickly save 5–7 minutes per paper. The trick is to treat all three as 'comparing parts' problems.
Do's
- DO convert every ratio into units the moment you read the question. '3 : 5' = 8 units, done.
- DO use a model for 'before and after' ratio questions — the bar diagram exposes which quantity stays constant.
- DO convert percentage to fraction when the numbers are messy. 12.5% = 1/8, 87.5% = 7/8 — memorise these.
- DO draw a table for rate problems: rate × time = work. Fill in what's given, solve for the missing slot.
- DO double-check whether a percentage is of the original or the new quantity ('decrease by 20%' vs '20% of'). Most careless losses hide here.
- DO write the full answer statement with the correct unit: 'Ans: 60 apples' not just '60'.
Don'ts
- DON'T add or subtract ratios directly — they must be converted to fractions or units first.
- DON'T ignore the phrase 'at this rate'. It tells you the quantities scale proportionally.
- DON'T round halfway through working. Round only once, at the very end.
- DON'T confuse '30% more' with '30% of'. Sketch it on the side if unsure.
- DON'T assume the unknown in a rate question is always the final answer — sometimes you need to solve for an intermediate rate first.
- DON'T spend 8 minutes on a single ratio question — bank the method mark with a labelled model and move on.
Ratio, percentage, rate — see the parts, fix the units, and the answer is usually one clean step away.
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