1999 AMC 12 Problem 8

Attempt Problem 8 of the 1999 AMC 12 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 1999 AMC 12 solutions, or check the answer key.

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8.

At the end of 19941994 Walter was half as old as his grandmother. The sum of the years in which they were born is 3838.3838. How old will Walter be at the end of 1999?1999?

4848

4949

5353

5555

101101

Answer: D
Concepts:ageslinear equation
Difficulty rating: 1240
Solution:

Let Walter be ww years old at the end of 1994,1994, so his grandmother is 2w.2w. Their birth years are 1994w1994 - w and 19942w,1994 - 2w, and (1994w)+(19942w)=3838. \begin{aligned} &(1994 - w) \\ &\quad {}+ (1994 - 2w) = 3838. \end{aligned} This gives 39883w=3838,3988 - 3w = 3838, so w=50.w = 50.

At the end of 1999,1999, Walter will be 50+5=55.50 + 5 = 55.

Thus, the correct answer is D.

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