Question 392182: Suppose that the credit remaining on a phone card (in dollars) is a linear function of the total calling time (in minutes). When graphed, the function gives a line with a slope of -0.14. See the figure below.
There is $26.02 in credit remaining on the card after 43 minutes of calls. How much credit was there after 32 minutes of calls?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Suppose that the credit remaining on a phone card (in dollars) is a linear function of the total calling time (in minutes).
--
credit = m(call time) + b
============================
When graphed, the function gives a line with a slope of -0.14.
---
m = -0.14
============================
See the figure below.
---
No figure shown
=============================
There is $26.02 in credit remaining on the card after 43 minutes of calls.
26.02 = -0.14(43) + b
b = 26.02+6.02
b = 32.04
==============================
C(x) = -0.14x+32.04
---
How much credit was there after 32 minutes of calls?
C(32) = -0.14(32) + 32.04
C(32) = $27.56
===================
Cheers,
Stan H.
|
|
|
