82
Explanation
the average is calculated by dividing the sum of the values in the set by their number.
Step 1
Let
[tex]\begin{gathered} \text{set}=\lbrace87,79,84,70,90\rbrace \\ the\text{ sum of the values is=87+79+84+70+90}=410 \\ n\text{umber of values= 5} \end{gathered}[/tex]Step 2
apply the equation
[tex]\text{Average}=\text{ }\frac{the\text{ sum of the values}}{\nu mber\text{ of values}}=\frac{410}{5}=82[/tex]so, the answer is 82
