Formative Assessment 122

Assessment Problem: 

Phone Cost Problem
The Jog Phone Company is currently offering a calling plan that charges 10¢ per minute for the first 5 minutes for any phone call. Any additional minutes cost only 6¢ per minute.
1. How much would a 3-minute phone call cost? An 8-minute phone call? A 15-minute phone call? Explain how you determined these.
2. How much would a 123-minute phone call cost? Explain how you determined this.
3. Suppose that a certain phone call (using the Jog Company plan) costs $4.64. How many minutes long was the call? Explain how you determined this.
4. Explain how you would determine the cost for any number of minutes under this plan. Write a formula to explain how you would determine this cost.

Patterns & Functions
Common Core Standards: 
Research References: 
Lannin, J. K., Barker, D. D., & Townsend, B. E. (2006).