a real estate agent is considering changing her cell phone plan. there are 3 plans to choose from, all of which involve a weekly service charge of $20. plan A has a cost of $0.45/min for daytime calls and $0.20/min for evening calls. plan B has a charge of $0.55/min for daytime calls and $0.15/min for evening calls. plan C has a flat rate of $80 with 200 minutes of calls allowed per week and a charge of $0.40 per minute beyond that, day or evening.
-determine the total charge under each plan for this case: 120 minutes of days calls and 40 minutes of evening calls in a week
-prepare a graph that shows total weekly cost for each plan versus daytime call minutes
-if the agent will use the service for daytime calls, over what range of call minutes will each plan be optimal?
-suppose that the agent expects both daytime and evening calls. at what point (i.e. percentage of call minutes for daytime calls) would she be indifferent between plans A and B?