Problems

A bank has six tellers. Use the following information to answer Problems 1–4:

• Mean service time equals 1 minute.

• Mean interarrival time equals 25 seconds.

• Standard deviation of service times equals 1 minute.

• Standard deviation of interarrival times equals 10 seconds.

1. Determine the average time a customer waits in line.

2. On average, how many customers are present in the bank line?

3. Would you recommend adding more tellers?

4. Suppose it costs $20 per hour to have a teller working and we value a customer’s time at $15 per hour. How many tellers should we have working?