SOLUTION: 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

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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.
A. 51 minutes B. 1 hour 57 minutes C. 2 hours 31 minutes
D. 5 hours 51 minutes
Could someone please help me with this math problem?
Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
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