Question 614039
Sally is comparing Sprint to Verizon cell phone rates.
Sprint charges $25.00 per month plus and .10 per minute for the use of the phone.
 Verizon charges $10.00 per month and .20 per minute for the use of the phone.
 How long per month would Sally have to use her phone to make Sprint the better choice.
:
Let m = no. minutes she uses in one month
:
Write an equation for the cost of each plan (per month)
:
Sprint
cost = .10m + 25 
Verizon
cost = .20m + 10
:
Write an equation for the statement
"Verizon cost more than Sprint"
.20m + 10 > .10m + 25
.20m - .10m > 25 - 10
.10m > 15
m > 15/.10
m > 150 minutes
:
If she talks 151 min or more the Sprint plan is better
:
:
Prove this to yourself>
Sprint
 C = .10(151) + 25
 C = 15.10 + 25
 C = $40.10
Verizon
 C = .20(151) + 25
 C = 30.20 + 10
 C = $40.30