Problem 12 · 2013 Math Kangaroo
Medium
Arithmetic & Operations
careful-counting
Pinocchio’s nose is 9 cm long. Each time he lies, his nose grows by 6 cm. Each time he tells the truth, it shrinks by 2 cm. He tells three lies and twice tells the truth. How long is Pinocchio’s nose now?
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Answer: D — 23 cm
Show hints
Hint 1 of 3
Each lie adds 6 cm to the nose; each truth takes 2 cm away.
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Hint 2 of 3
There are three lies and two truths, so work out the total growing and the total shrinking.
Still stuck? Show hint 3 →
Hint 3 of 3
Start at 9 cm, add all the growing, then take away all the shrinking.
Show solution
Approach: add the lies, subtract the truths
- Three lies add 3 × 6 = 18 cm; two truths take off 2 × 2 = 4 cm.
- 9 + 18 − 4 = 23 cm.
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