The manager of a tourist attraction is concerned with negative customer reviews regarding the waiting time to enter the attraction. Analyzing the historical data for waiting times on Sunday, there are two waves of peak customer arrivals - 10am-12pm and 2pm-4pm. During these times, customers arrive at the rate of 1 customer per minute. The attraction opening times are between 9am and 6pm, customers stop arriving at 5pm and the arrival rate outside of peak hours is 0.5 customer per minute. Admission to the attraction requires a ticket purchase and takes 3 minutes on average. At all times, there are two admission check-points (registers).

Ignoring any unpredictable variability in both arrivals and processing times and assuming a continuous/fluid and deterministic flow of customer, construct a build-up diagram to answer the following questions:

1. What is the maximum number of customers waiting for admission to the attraction? Assume customers do not leave after arriving to the attraction.

2. How many customers are not able to enter the attraction before closing at 6pm?

3. The manager decides to install an additional admission point to be staffed on Sunday afternoons. How many minutes before the last customer arrives would the addition register need to start working so that all customers enter the attraction by 5pm?