3.3.3. Suppose the lifetime in months of an engine, working under hazardous conditions, has a Γ distribution with a mean of 10 months and a variance of 20 months squared. (a) Determine the median lifetime of an engine. (b) Suppose such an engine is termed successful if its lifetime exceeds 15 months. In a sample of 10 engines, determine the probability of at least 3 successful engines.
