Consider the concierge service at a large resort.The concierge helps guests with various tasks including reservations at local restaurants or offering advice on various local activities On average, 12 guests arrive at the concierge desk per hour (the standard deviation of the inter- arrival times is equal to 5 minutes). The hotel has only one concierge on service. It takes the concierge, on average, 4 minutes to help the guest with their questions. The standard deviation of this time is three minutes
1. What is the average time a guest has to wait before talking to the concierge?