Mean or Expected Value and Standard Deviation · Exercise 27

Suppose that the PDF for the number of years it takes to earn a Bachelor of Science (B.S.) degree is given as in.

$$\begin{array}{cc}\text{x}& \text{P(x)}\\ \text{3}& \text{0.05}\\ \text{4}& \text{0.40}\\ \text{5}& \text{0.30}\\ \text{6}& \text{0.15}\\ \text{7}& \text{0.10}\end{array}$$
On average, how many years do you expect it to take for an individual to earn a B.S.?

OpenStax, Introductory Statistics 2e · §4.2 Mean or Expected Value and Standard Deviation · Exercise 27