Problem 22 · 2021 Math Kangaroo
Stretch
Counting & Probability
careful-counting
Each participant in a cooking contest baked one tray of cookies like the one shown beside. What is the smallest number of trays of cookies needed to make the following plate?
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Answer: C — 3
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Hint 1 of 3
Count how many of each kind of cookie the big plate needs.
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Hint 2 of 3
Now see how many of each kind you get from just one tray.
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Hint 3 of 3
The kind of cookie you need the most of decides how many trays you must bake.
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Approach: compare each cookie type to what one tray gives
- Count each kind of cookie on the plate, and count how many of that kind one tray makes.
- For each kind, see how many trays it would take, then pick the biggest of those numbers.
- Three trays are enough to cover every kind, so the answer is 3.
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