3. At my favourite coffee shop customers wait patiently in line for great service. Customers are served with a first come first serve basis. Experience shows that about 15 new customers arrive, on average, every hour. The time between arrivals is random. The owner tells you that the barista can serve an average of 20 customers per hour. Service time of customer is exponentially distributed i.e. a few customers place complex orders that take longer to make but most customers place simple orders that are quick to make. Answer the following questions:

A. The barista is busy ___________% of the time. (explain. Creative explanations are good)

B. On average how many people will you find in line + waiting for their coffee at any given time = ________

C. On average the customer will wait for _______ minutes for his coffee from the time he/she comes in; of that _______ minutes will be spent in line.

D. The great barista got a new job and the coffee shop hired a junior barista. Also at the same time traffic increased. The change was that 20 people started showing up at the coffee shop every hour, on average and the barista being new could only serve 15 customers, on average, per hour. Do your previous answers change?