Problem 13 · 2010 Math Kangaroo
Medium
Counting & Probability
careful-counting
Kangi walks straight from the zoo to the school (Schule) and counts the flowers along the way. Which of these numbers can he not get this way?
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Answer: C — 11
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Hint 1 of 2
He can take either branch of the first loop and either branch of the second loop, always crossing the middle.
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Hint 2 of 2
Add up the flowers for each route choice and see which of the listed totals never comes out.
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Approach: add the flowers for every route and find the missing total
- The walk has a choice in the first loop, the fixed middle path, and a choice in the second loop.
- Adding the flowers for the four possible routes gives several totals.
- The number that none of the routes produces is 11.
Mark:
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