Gubser Welding operates a welding repair shop. Assume that the arrival of jobs follows a Poisson arrival process with an average of 2 jobs in an 7 hour day. The time required to complete a job follows a normal distribution with mean time of 2.5 hours and standard deviation of 4 minutes. Assume 1 welder completes the jobs.

What is the average time (hours) a job waits before the mechanic can work on it (average time in the line)

a. 3.127 hours

b. 5.627 hours

c. 337.6 minutes

d. none of the above