2007 AMC 12B Problem 8

Attempt Problem 8 of the 2007 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 2007 AMC 12B solutions, or check the answer key.

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8.

Tom's age is TT years, which is also the sum of the ages of his three children. His age NN years ago was twice the sum of their ages then. What is T/N?T/N?

22

33

44

55

66

Answer: D
Concepts:ageslinear equation
Difficulty rating: 1290
Solution:

Tom's age NN years ago was TN.T-N. His three children were each NN years younger, so their ages then totaled T3N.T-3N.

The condition gives TN=2(T3N), T-N=2(T-3N), so 5N=T5N=T and T/N=5.T/N=5.

Thus, the correct answer is D.

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