2004 AMC 8 Problem 9 — Solution | LIVE by Po-Shen Loh

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2004 AMC 8 Problem 9

Attempt Problem 9 of the 2004 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 2004 AMC 8 solutions, or check the answer key.

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

9.

The average of the five numbers in a list is $54.$ The average of the first two numbers is $48.$ What is the average of the last three numbers?

$55$

$56$

$57$

$58$

$59$

Answer: D

Concepts:mean

Difficulty rating: 1020

Solution:

The sum of all $5$ numbers is $54 \cdot 5 = 270.$ The sum of the first $2$ numbers is $48 \cdot 2 = 96.$

The sum of the last $3$ numbers is $270 - 96 = 174.$ The average is therefore $174 \div 3 = 58.$

Thus, D is the correct answer.

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