Problem 8 · 2025 Math Kangaroo
Medium
Fractions, Decimals & Percents
percent-multiplier
Silvia's favourite chocolate bars are sold in packets. There used to be five bars in each packet. Now there are only four in each packet, but the packets still cost the same. By how many percent has each bar become more expensive?
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Answer: C — by 25%
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Hint 1 of 2
Find the cost of one bar before and after the change.
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Hint 2 of 2
Old price per bar is P/5, new is P/4; compare them as a ratio.
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Approach: compare unit prices
- Old price per bar = P/5; new price per bar = P/4.
- Ratio = (P/4)/(P/5) = 5/4, an increase of 25%.
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