An international business operation manager is considering buying a smartphone and phone service plan. There are three service plans to choose from, all of which involve a weeklycharge of $25. Plan A has a cost of $0.35a minute for daytime calls and $0.10a minute for evening/night/weekend calls. Plan B has a charge of $0.45a minute for day time calls and a charge of $0.05a minute for evening/night/weekend calls. Plan C has a flat rate of $75with 200 minutes of calls allowed per week and a cost of $0.30 per minutes beyond that, day or evening/night/weekend.

a. Determine the total fee under each plan for this case: 150 minutes of daytime calls and 50 minutes of evening/night/weekend calls in a week.

b. Prepare a graph that shows total weekly day time cost for each plan against daytime call minutes.

c. If the manager plans to use the service for only daytime calls, over what range of call minutes will each plan be optimal.

d. Suppose that the manager expects both daytime and evening/night/weekend calls. At what percentage of calls minutes for daytime calls would she be indifferent between plans A and B?