Problem 9 · 2024 Math Kangaroo
Medium
patterns
cycleskip-counting
Marina draws five pictures in a fixed order (a cloud, a ghost, a cat, a moon, and a flame), then repeats the same five over and over again. Which picture is the 27th picture?
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Answer: B
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Hint 1 of 3
The pictures come in repeating groups of five, always in the same order.
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Hint 2 of 3
Count by fives to get close to 27 without drawing them all out.
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Hint 3 of 3
After five whole groups you have drawn 25 pictures, so just keep going from there.
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Approach: count in groups of five
- The five pictures repeat as a group, so skip-count: 5, 10, 15, 20, 25 finishes five whole groups.
- Picture 25 is the last one of a group (the flame), so picture 26 starts a new group with the 1st picture (the cloud).
- Picture 27 is then the 2nd picture of the group — the ghost, option B.
Mark:
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