Please provide full solution in excel showing formulas. Thank you, i will give thumbs up.

3. Trucks arrive at the loading dock of a Walmart store at an average rate of 1.2 per hour in the mornings. A single crew consisting of two workers is able to load a truck in 30 minutes. Each worker receives $10 per hour in wage and benefits, and trucks and drivers impose an hourly cost of $60. The management is evaluating whether adding one or two members to the crew is economical. The average service rate for the three-worker case is estimated at 2.4 trucks per hour. This rate for the four-worker crew is estimated at 2.6 trucks per hour. Assume Poisson arrivals and Exponential service durations. What is the optimal number of crew members (i.e., among two, three and four, which crew size minimizes the total cost)