Question

What is the mean of the set of numbers, {–11, 22, –2, –3}? A. –6.5 B. –1.5 C. 1.5 D. 6.5

Answer 1

$\dfrac{-11+22+(-2)+(-3)}{4}=\dfrac{22-16}{4}=\dfrac{6}{4}=\fbox{1.5}\to\fbox{C.}$

Answer 2

Since there are four numbers in the set, their mean (average) is calculated by dividing by four their sum. 
  Sum = -11 + 22 + -2 + -3 = 6
Dividing the sum by four gives an answer which is equal to 1.5. Thus, the answer is letter C.