The following information pertains to telephone calls to a motel switchboard on a typical

The following information pertains to telephone calls to a motel switchboard on a typical
Tuesday. Use Table 1.
Period
Incoming
Rate (calls
per minute)
Service
Rate (calls
per minute
per
operator)
Number of
Operators
Morning 1.6 1.6 2
Afternoon 2.7 .9 4
Evening 1.5 .6 3
a.
Determine the average time callers wait to have their calls answered for each period and the
probability that a caller will have to wait for each period. (Round intermediate calculations
and final answers to 3 decimal places.)
Period Pw
Morning
Afternoon
Evening

b.
Determine the maximum line length for a probability of 91 percent. (Round your
intermediate calculations to 3 decimal places and round up your final answers to the
next whole number.)
Period Lmax
Morning
Afternoon
Evening

Trucks are required to pass through a weighing station so that they can be checked for weight
violations. Trucks arrive at the station at the rate of 24 an hour between 7:00 p.m. and 9:00 p.m.
Currently two inspectors are on duty during those hours, each of whom can inspect 15 trucks an
hour.
Use Table 1.
a.
How many trucks would you expect to see at the weighing station, including those being

Ls
trucks
b.
If a truck was just arriving at the station, about how many minutes could the driver expect to
Ws
min.
c.
What is the probability that both inspectors would be busy at the same time?(Round your
Pw
d.
How many minutes, on average, would a truck that is not immediately inspected have to
Wa
min.
f.
What is the maximum line length for a probability of .90? (Round up your answer to the
next whole number.)
L max

banking hours. During the early evening hours in the summer months, customers arrive at a
certain location at the rate of one every other minute. This can be modeled using a Poisson
distribution. Each customer spends an average of 90 seconds completing his or her transactions.
Transaction time is exponentially distributed.
a.
Determine the average time customers spend at the machine, including waiting in line and
the nearest whole number.)
Average time minutes
b.
Determine the probability that a customer will not have to wait upon arriving at the automatic
Probability
c.
Determine the average number waiting to use the machine. (Round your answer to 2
decimal places.)
Average number customers

constant. Customers arrive at a mean rate of 75 per hour, and this rate is Poisson-distributed.
a.
Determine the average number of customers waiting in line. (Round your answer to 2
decimal places.)
Average number of customer
b.
Determine the average time customers spend in the system. (Do not round intermediate
Average time minutes
c.
Determine the average number in the system. (Do not round intermediate calculations.
Average number

Repair calls are handled by one repairman at a photocopy shop. Repair time, including travel
time, is exponentially distributed, with a mean of 2.5 hours per call. Requests for copier repairs
come in at a mean rate of 2.1 per eight-hour day (assume Poisson).
_2013_QC_28691
a.
Determine the average number of customers awaiting repairs. (Round your answer to 2
decimal places.)
Number of customers
b.
Determine system utilization. (Round your answer to the nearest whole percent. Omit the
System utilization %
c.
Determine the amount of time during an eight-hour day that the repairman is not out on a