Problem 22 · 2021 Math Kangaroo
Stretch
Ratios, Rates & Proportions
proportiontotal-then-divide
Maurice asked the canteen chef for the recipe for his pancakes. The recipe makes 100 pancakes and uses 25 eggs, 4 litres of milk, 5 kg of flour and 1 kg of butter. Maurice has 6 eggs, 400 g flour, 0.5 litres of milk and 200 g butter. What is the largest number of pancakes he can make using this recipe?
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Answer: B — 8
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Hint 1 of 2
The recipe makes 100 pancakes; for each ingredient work out how many pancakes Maurice's amount allows.
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Hint 2 of 2
The ingredient that runs out first sets the limit — take the smallest of the four.
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Approach: find the limiting ingredient
- Per 100 pancakes: 25 eggs, 4 L milk, 5 kg (5000 g) flour, 1 kg (1000 g) butter.
- Maurice's stock allows: eggs 6/25×100=24, milk 0.5/4×100=12.5, flour 400/5000×100=8, butter 200/1000×100=20.
- Flour runs out first, so the most he can make is 8.
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