2008 AMC 8 Problem 10

Attempt Problem 10 of the 2008 AMC 8 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 2008 AMC 8 solutions, or check the answer key.

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10.

The average age of the 66 people in Room A is 40.40. The average age of the 44 people in Room B is 25.25. If the two groups are combined, what is the average age of all the people?

 32.5 \ 32.5

 33 \ 33

 33.5 \ 33.5

 34 \ 34

 35 \ 35

Answer: D
Concepts:mean
Difficulty rating: 960
Solution:

The sum of the ages in Room A is 640=240.6\cdot 40 = 240.

The sum of the ages in Room B is 425=100.4\cdot 25 = 100.

The total sum is 240+100=340.240+100 = 340.

The average is therefore 34010=34.\dfrac{340}{10} =34.

Thus, the answer is D .

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