busy intersection was recorded for a year. There were 4 weeks with no accidents, 26 weeks with one accident, 13 weeks with
two accidents, and 9 weeks with three accidents. A week is to be selected at random and the number of accidents noted. Let X be the outcome. Then X is a random variable taking on the values 0, 1, 2, and 3.
(a) Write out a probability table for X.
(b) Compute E(X).
(c) Interpret E(X).
(a) Fill in the following probability table with the correct values.
Outcomes
0
1
(Accidents per week)
2
3
Probability
(Type simplified fractions.)
(b) Compute the expected value, E(X).
E(X) =
(c) Which of the following is a valid interpretation of the value of E(X)?
A. E(X) is the standard deviation of the annual accident rate.
B. E(X) is the average number of accidents per week in a given year.
C. E(X) is the average number of weeks with 0-3 accidents.
D. E(X) is probability of an accident occuring at any given time.
E. E(X) is the percentage of cars driving through this intersection that are involved in accidents.
