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2005 AMC 12A Problem 5

Problem 5 of 25EasierProbability & Statistics

The average (mean) of 2020 numbers is 30,30, and the average of 3030 other numbers is 20.20. What is the average of all 5050 numbers?

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Solution

The total of all 5050 numbers is 20⋅30+30⋅2020 \cdot 30 + 30 \cdot 20 =600+600= 600 + 600 =1200.= 1200. The average is 1200÷50=24.1200 \div 50 = 24. Thus, the correct answer is B.
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