Chapter 1.CR, Problem 9CR

Reminder Round all answers to two decimal places unless otherwise indicated.

9. Cell Phone Charges Again One cell phone plan charges a flat monthly rate of $\$34.95$ with extra charges of $\$0.35$ per minute for each minute after the first $4000$ minutes and $\$0.10$ per text message after the first $100$ text messages.

a. Choose letters to represent the variables.

b. Write a formula to express the cell phone charges as a function of the number of minutes used (assume that the number is at least $4000$) and the number of text messages (assume that the number is at least $100$).

c. What are your cell phone charges if you use $6000$ minutes and $450$ text messages?

d. Write the formula to express the cell phone charges, this assuming that the minutes are at least $4000$, but the number of text message is less than $100$.

e. What are your cell phone charges if you use $4200$ minutes and $88$ text messages?