18. A certain company has compiled a list of 3 people who are qualified for a certain important job, and would be willing to be hired at any time. But the job is underpaid; and anyone who is hired for...

Just solve part b please

Extracted text: 18. A certain company has compiled a list of 3 people who are qualified for a certain important job, and would be willing to be hired at any time. But the job is underpaid; and anyone who is hired for it will get a better offer and leave at an unpredictable time, on average, after 3.5 years on the job. a) What are the expectation and standard deviation of the number of years until the company uses up the list of qualified people, and must seek more candidates? b) What is the probability the company will have used up the list within 8.0 years?