2014 AMC 10A Problem 5

Below is the professionally curated solution for Problem 5 of the 2014 AMC 10A, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2014 AMC 10A solutions, or check the answer key.

All of the real AMC 8, AMC 10, AMC 12, and AIME problems in our complete solution collection are used with official legal permission of the Mathematical Association of America (MAA).

Concepts:meanmedian (data)

Difficulty rating: 1280

5.

On an algebra quiz, 10%10\% of the students scored 7070 points, 35%35\% scored 8080 points, 30%30\% scored 9090 points, and the rest scored 100100 points. What is the difference between the mean and median score of the students' scores on this quiz?

11

22

33

44

55

Solution:

The median is 9090, because 45%45\% of the students scored below 9090 and 25%25\% scored above 9090.

The mean is 0.1070+0.3580+0.3090+0.25100=870.10\cdot70+0.35\cdot80+0.30\cdot90+0.25\cdot100=87.

The difference is 9087=390-87=3.

Thus, C is the correct answer.

Problem 5 in Other Years