2009 AMC 12A Problem 4

Attempt Problem 4 of the 2009 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 2009 AMC 12A solutions, or check the answer key.

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4.

Four coins are picked out of a piggy bank that contains a collection of pennies, nickels, dimes, and quarters. Which of the following could not be the total value of the four coins, in cents?

1515

2525

3535

4545

5555

Answer: A
Concepts:moneymultiplecasework
Difficulty rating: 1200
Solution:

If the four coins include a penny, the total is not a multiple of 5,5, so it cannot equal any of the five listed multiples of 5.5. If there is no penny, every coin is worth at least 55 cents, so the total is at least 2020 cents. Either way, 1515 is impossible.

The other amounts are attainable: 25=10+5+5+5,25 = 10 + 5 + 5 + 5, 35=10+10+10+5,35 = 10 + 10 + 10 + 5, 45=25+10+5+5,45 = 25 + 10 + 5 + 5, and 55=25+10+10+10.55 = 25 + 10 + 10 + 10.

Thus, the correct answer is A.

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