2014 AMC 8 Problem 24

Below is the professionally curated solution for Problem 24 of the 2014 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2014 AMC 8 solutions, or check the answer key.

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Concepts:median (data)optimization

Difficulty rating: 1560

24.

One day the Beverage Barn sold 252252 cans of soda to 100100 customers, and every customer bought at least one can of soda. What is the maximum possible median number of cans of soda bought per customer on that day?

2.5 2.5

3.0 3.0

3.5 3.5

4.0 4.0

4.5 4.5

Solution:

Order the 100100 purchases from least to greatest. The median is the average of the 5050th and 5151st entries. To maximize it, make the first 4949 entries as small as possible, so set them all equal to 11.

If the 5050th entry were at least 44, then the total would be at least 49+514=25349+51\cdot4=253, too many cans. So the 5050th entry is at most 33.

This maximum is attainable: use 4949 entries equal to 11, the 5050th entry equal to 33, and the final 5050 entries equal to 44. The total is 49+3+504=25249+3+50\cdot4=252, and the median is (3+4)/2=3.5(3+4)/2=3.5.

Thus, C is the correct answer.

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