Question

Mr. Williams trains a group of student athletes. He wants to know how they are improving in the number of push-ups they can do.

These dot plots show the number of push-ups each student was able to do last month and this month.


How much did the mean number of push-ups increase from last month to this month?


Question 1 options:


2.75 more push-ups



4.375 more push-ups



7.5 more push-ups



There is not enough information given to answer the question.

Answer 1

7.5 more push-ups

Explanation:

From the dot plot attached :

Last month mean :

Σfx/Σf

Σfx = [(10*2)+(15*2)+(25*3)+(35*1)] = 160

Σf = (2 + 2 + 3 + 1) = 8

Mean = 160 / 8 = 20

This month mean :

Σfx/Σf

Σfx = [(10*1)+(15*1)+(25*1)+(30*3)+(40*2)] = 220

Σf = (1 + 1 + 1 + 3 + 2) = 8

Mean = 220/8

Mean = 27.5

Difference in mean :

This month mean - Last month mean

27.5 - 20

= 7.5