Question

In a certain​ city, projections for the next year indicate there is a​ 20% chance that electronics jobs will increase by 1100
​,
a​ 50% chance that they will increase by 400
​,
and a​ 30% chance they will decrease by 800
.
Find the expected change in the number of electronics jobs in that city in the next year.

Answer 1

$$\begin{array}{c:c:c} X & P(X) & XP(X) \\ \hline 1100 & 0.2 & 220 \\ \hdashline 400 & 0.5 &200 \\ \hdashline -800 & 0.3 & -240 \\ \hline Total &1 & 180 \end{array}$$

$$1100(0.2)+400(0.5)-800(0.3)=180$$

Expectation is a increase of 180.