Problem 21 · 2018 Math Kangaroo
Stretch
Geometry & Measurement
careful-counting
A belt can be closed in 5 different holes (see picture). How many cm longer is the belt if it is closed in the first hole instead of in the fifth (last) hole?
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Answer: B — 8 cm
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Hint 1 of 2
The holes are spaced 2 cm apart; using the first hole leaves more belt than using the fifth.
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Hint 2 of 2
The extra length is the distance from the first hole to the fifth.
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Approach: measure the gap between the first and last hole
- The five holes are 2 cm apart, so the first and fifth holes are 4 × 2 = 8 cm apart.
- Closing in the first hole instead of the fifth leaves that extra 8 cm of belt.
- So the belt is 8 cm longer.
Mark:
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