Part A) Minimum cost = $30
Part B) Value of f(150) = $30
Part C) m = 275 minutes
Part D) Cost per minute after 200 minutes = $0.2
Explanations:From the graph shown:
Monthly rate for 200 minutes for phone calls = $30
An additional fee is charged for more than 200 minutes for phone calls
Part A) The minimum monthly cost of Corinne's cell phone plan.
Note that the minimum monthly cost of Corinne's cell phone plan will be when he does not use more than 200 minutes for phone calls.
Therefore, the minimum monthly cost, C = f(200) = $30
Part B)
The value of f(150)
f(150) means the cost of Corinne's cell phone plan when 150 minutes is spent for phone calls, i.e. m = 150
Since there is a flat rate of $30 for 0 to 200 minutes, f(150) = $30
Part C)
For what m is f(m) = 55
This means that we should find the number of minutes spent when the cost of the plan is $55
From the graph, $55 is charged at 275 minutes
Therefore, when f(m) = 55, m = 275 minutes
Part D)
Cost per minutes after the monthly allowance of 200 minutes
After the monthly allowance of 200 minutes, we would notice that, for every 50 minutes, there is a $10 charge. That means that for every 1 minute, there will be a charge of 10/50 = $0.2
Cost per minute = $0.2