VP rates: $30 installation and 12¢a minute.
VTT: $50 installation and 9¢a minute.
What is the best buy? (Installation charges are one time fee. But can we assume that summer people just have the one installation? Or do the phone companies charge the fee every year?)
We need at least 3 methods to solve the problem: graphing, a table, and simultaneous equations.
The graph is above BUT I can't figure out in this new version of Excel that I have how to adjust the scale. As soon as I get my hands on the older version on Monday, I'll fix it up in a jiffy.
Tables:
Equations:
The equations:
VP: y = 30 + 0.12x
VTT: y = 50 + 0.09x
3(y = 30 + 0.12x)
-4(y = 50 + 0.09x)
3y = 90 + 0.36x
-4y = -200 - 0.36x
-y = -110
y = 110
if y = 110, then:
110 = 30 + 0.12x
80 = 0.12x
666.67 = x
The graphs will intersect at (666.67 minutes, $110)
3y = 90 + 0.36x
-4y = -200 - 0.36x
-y = -110
y = 110
if y = 110, then:
110 = 30 + 0.12x
80 = 0.12x
666.67 = x
The graphs will intersect at (666.67 minutes, $110)
No comments:
Post a Comment
Thank you for visiting and for your comments!