Each department at mark's company employs 25 people. there are 9 departments. each person will be transported by bus to a training session. each bus can hold 48 people. how many buses will be needed?
a. 4
b. 5
c. 8
d. 11

How do you calculate the mean (average) ?
Isn't it just

  Mean = (total points of all the tests) divided by (number of tests)  ?

Let's work with that.

Multiply each side of that formula by (number of tests), and you have

       Total points of all the tests  =  (Mean) times (number of tests).

In this problem, you know the mean, and you know the number of tests,
so you can easily calculate the total points.