SOLUTION: Lisa is trying to work out the best phone deal. AT&T is offering long distance service for $0.04/minute after paying a flat $7.00/month. Ameritech will charge $0.07/minute and NO

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Question 88681: Lisa is trying to work out the best phone deal. AT&T is offering long distance service for $0.04/minute after paying a flat $7.00/month. Ameritech will charge $0.07/minute and NO monthly payments. Under what conditions is AT&T the better deal? When is Ameritech the better deal?


Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Lisa is trying to work out the best phone deal. AT&T is offering long distance service for $0.04/minute after paying a flat $7.00/month. Ameritech will charge $0.07/minute and NO monthly payments. Under what conditions is AT&T the better deal? When is Ameritech the better deal?
:
Let x = no. of minutes
:
At&t cost = .04x + 7
:
Ameritech cost = .07x
:
at&t cost exceeds Ameritech cost
.04x + 7 > .07x
.04x - .07x > = -7
-.03x > -7
+.03x < +7; multiplied eq by -1, reverses the inequality sign
x < 7/.03
x < 233.33 min, Ameritech is best