2012 AMC 12A Problem 2

Attempt Problem 2 of the 2012 AMC 12A 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 2012 AMC 12A solutions, or check the answer key.

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

Cagney can frost a cupcake every $20$ seconds and Lacey can frost a cupcake every $30$ seconds. Working together, how many cupcakes can they frost in $5$ minutes?

$10$

$15$

$20$

$25$

$30$

Answer: D

Concepts:rate unit conversion

Difficulty rating: 880

Solution:

In $5$ minutes there are $300$ seconds. Cagney frosts $\dfrac{300}{20} = 15$ cupcakes and Lacey frosts $\dfrac{300}{30} = 10$ cupcakes.

Together they frost $15 + 10 = 25$ cupcakes.

Thus, the correct answer is D.

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