11. An automobile service facility specializing in engine tune-ups knows that 45% of all tune-ups are done on four-cylinder automobiles, 40% on six-cylinder automobiles, and 15% on eight-cylinder automobiles. Let X
the number of cylinders on the next car to be tuned.

a. What is the pmf of X?

b. Draw both a line graph and a probability histogram for the pmf of part (a).

c. What is the probability that the next car tuned has at least six cylinders? More than six cylinders?