2009 AMC 12B Problem 3

Attempt Problem 3 of the 2009 AMC 12B below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2009 AMC 12B solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

3.

Twenty percent less than 6060 is one-third more than what number?
1616
3030
3232
3636
4848
Answer: D
Concepts:percentagefractionlinear equation
Small hint:
Twenty percent less than 6060 is 0.8⋅600.8 \cdot 60
Big hint:
One-third more than a number nn is 43n\dfrac{4}{3}n
Solution:
Twenty percent less than 6060 is 0.8⋅60=48.0.8 \cdot 60 = 48.
One-third more than nn is 43n,\dfrac{4}{3}n, so 43n=48\dfrac{4}{3}n = 48 gives n=36.n = 36.
Thus, the correct answer is D.
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