Question

What is the average (arithmetic mean) of all the multiples of ten from 10 to 190 inclusive?

Answer 1

. In a class of 78 students 41 are taking French, 22 are taking German. Of the students taking French or German, 9 are taking both courses. How many students are not enrolled in either course?

Answer 2

For the first question, do you agree that this statement is true:

The average of a finite Arithmetic Series is always the average of first term and last term.
@RanandoOnley

Answer 3

for the second question, you need Venn diagram

Answer 4

10 190
20 180
40 160
80 120
100 100 <== That seems a good candidate.