Question

The advertising agency counted the number of billboards in each city in the state. Number of billboards Number of cities 2 85 2 96 3 125 2 154 1 X is the number of billboards that a randomly chosen city has. What is the expected value of X? Write your answer as a decimal.

Answer 1

In order to calculate the expected value of x, we can just calculate the total number of billboards over the total number of cities. So we have:

$\begin{gathered} E(x)=\frac{2\cdot4+2\cdot85+3\cdot96+2\cdot125+1\cdot154}{2+2+3+2+1} \\ E(x)=\frac{870}{10} \\ E(x)=87 \end{gathered}$

So the expected value of x is 87.