probability

a. Consider writing onto a computer disk and then sending it through a certi er that counts the num- ber of missing pulses. Suppose this number X has a Poisson distribution with parameter l = .2. (Sug- gested in Average Sample Number for Semi- Curtailed Sampling Using the Poisson Distribu- tion, J. Qual. Tech., 1983: 126—129.)What is the probability that a disk has exactly one missing pulse?
b. What is the probability that a disk has at least two missing pulses?
c. If two disks are independently selected, what is the probability that neither contains a missing puls