Question

A class of 40 students took a test 20 students had an average score of 65. the other students had an average score of 52. what is the average score of the whole class?

At a health club, 28% of the members are men, the rest are women. If the average man is 33 years old, and the average woman is 38 years old, what is the average age of all the members?​

Answer 1

One: 58.5

Two 36.6

Explanation:

One

20 students * 65 = 1300 This is the total score of all 20 students. They may not all get 65, but 1300 is what their average total is.

20 students * 52 = 1040

The total score of all 40 students was 1300 + 1040 = 2340

The average for the entire class was 2340 / 40 = 58.5

Two

This question is done almost the same way.

Supposes the total number of members is 100. That means that 28 of them are men

28 * 33 = 924 This is the total age for the men

100 - 28 = 72 Out of 100, 72 of the people there are women.

72 * 38 = 2736

The total number of years of all of the members is

924 + 2736 = 3660

The average age of all members is 3660/100 = 36.6

Why did I pick 100 as the total membership? It is because a percentage is number out of 100. Am I allowed to invent things like that? Sure. I'm just using the definition of a percentage.

The average will make it come out the same.