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2014 Math Kangaroo

Problem 15

Problem 15 · 2014 Math Kangaroo Medium
Fractions, Decimals & Percents proportionwork-backward

The tail of the biggest crocodile in a zoo is one third of the crocodile’s total length. The head is 93 cm long and makes up one quarter of the length of the crocodile not counting its tail. How long is the crocodile?

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Answer: A — 558 cm
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Hint 1 of 2
Tail is 1/3 of the whole, so the rest (head + body) is 2/3 of the whole.
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Hint 2 of 2
The head is 1/4 of that 'rest', and the head is 93 cm.
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Approach: chain the two fractions back to the total
  1. Without the tail the crocodile is 2/3 of the total length.
  2. The head is 1/4 of that part: 93 = (1/4)(2/3 L) = L/6, so L = 558.
  3. The crocodile is 558 cm long.
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