Cellphone Plans

You are a representative for a handphone company and it is your job to promote different phone plans. 

• Plan A costs a basic fee of $29.95 per month and 10 cents per text message 

• Plan B costs a basic fee of $90.20 per month and has unlimited text messages

• Plan C costs a basic fee of $49.95 per month and 5 cents per text message 

• All plans offer unlimited calling
• Calling on nights and weekends are free
• Long distance calls are included

1. Determine the cost of each plan if you send 500 text messages in one month. Show your working out. 
Plan A cost $79.95 because on the graph, on plan A's line, the y coordinate for the x coordinate 500 is 79.95. The x coordinate is the number of text and the y coordinate is the cost.

Plan B cost $90.20 because the cost doesn't change from the number of text since it has no rate of change.

Plan C cost $74.95 because on the graph, on plan C's line, the y coordinate for the x coordinate 500 is 79.95. The x coordinate is the number of text and the y coordinate is the cost.

Plan A

Plan B

Plan C

2. Your boss asks you to visually display three plans and compare them so you can point out the advantages of each plan to your customers.

The Graph

3. A customer wants to know how to decide which plan will save her the most money. Determine which plan has the lowest cost given the number of text messages a customer is likely to send.
If you text 0 to 400 times in a month, then Plan A is the cheapest plan for you.
If you text 400 to 805 times in a month, then Plan B is the cheapest plan for you.

If you text more than 805 times in a month, then Plan C is the cheapest plan for you.