the second picture is the solution. i was wondering why =1.32. thank you

02 (Ref: Q. 18-20, p706): The number of customers coming to a bank between 1:00 and 1:30 p.m. of a "normal day has a Poisson distribution with an average of 39 customers during the half hour. The length of time each customer spends with a teller is Exponential with an average of 45.5 seconds. The average time a customer spends in the line waiting is desired to be three minutes. The manager is wondering! how many tellers are required during this time period. 20. [Multiple servers, Exponential service durations] 2 = 39/half hour = 1.3 customers/min. Avg. service time = 45.5 sec. u = 1.32 round to 1.3 customers/min. W should be = 3 min. M? 2/u= 1.3/1.3 = 1 M From Table 18-4 I W = 12 2 .333 .333/1. 3 26 min 15 see. Because 15 sec