Question

A local television station sells 15-second 30-second and 60-second advertising spots. Consider the random variable x= length of a randomly selected commercial appearing on this station, and suppose that the probability of distribution of x given by the following table. 

X 15 P(x) 0.1

X 30 P(x) 0.3

X 60 P(x) 0.6

What is the mean length for commercials appearing on this station?

Answer 1

The mean length:

$\mu=\sum x_ip(x_i)=15\cdot0.1+30\cdot0.3+60\cdot0.6=46.5$ seconds