5. suppose the probability distribution for x = number of jobs held during the past year for work
study students at a university is as follows:
x 0 1 2 3 4 5
f(x) .12 a .28 .18 .06 .02

a. find a.
b. find the probability that a randomly selected student held three or more jobs during the past
year.
c. find the cumulative distribution function.
d. find the e(x).
e. how many jobs would you expect a randomly selected student to hold in the past year?