Let X be the number of material anomalies occurring in a par…

Let X be the number of material anomalies occurring in a particular region of an aircraft gas-turbine disk. The article “Methodology for Probabilistic Life Prediction of Multiple-Anomaly Materials” (Amer. Inst. of Aeronautics and Astronautics J., 2006: 787–793) proposes a Poisson distribution for X. Suppose that the mean number of anomalies of a gas-turbine disk is 4. a. What is the probability that at most 6 anomalies are discovered on a single disk? b. What is the probability that between 3 and 9 anomalies are discovered on a single disk? c. What is the probability that the number of anomalies exceeds the mean number by no more than 2 deviations? d. If 2 disks are randomly selected, what is the probability that each disk would have at most one anomaly?