Answer: The attendant’s expected earn- ings for the period between 4:00 P.M and 5:00 P.M is $12,67.
Explanation: The discrete random variable X represent attendant’s earnings.
The expected value of the discrete random variable X is
= E (x) = ∑× f(x)
= 7 × 1/12 + 9 × 1/12 + 11 × 1/4 + 13 × 1/4 + 15 × 1/6 + 17 × 1/6 = 12,67.