Problem 14 · 2010 Math Kangaroo
Medium
Ratios, Rates & Proportions
proportion
In order to sew together three short strips of cloth to get one long strip, Cathy needs 18 minutes. How much time does she need to sew together a really long piece consisting of six short strips?
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Answer: D — 45 minutes
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Hint 1 of 2
Joining strips needs one fewer seam than the number of strips.
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Hint 2 of 2
Find the time per seam from the three-strip case, then count seams for six strips.
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Approach: count seams, scale by time per seam
- Three strips need 2 seams and take 18 min, so each seam takes 9 min.
- Six strips need 5 seams: 5×9 = 45 minutes.
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