word problem; slope y-intercept

Question

A cell phone plan costs $25 per month, plus $5 for every gigabyte of data usage. 

a. Describe the cost vs data usage relation with a linear equation where y is the monthly cost and x is the number of gigabytes of data accessed during the month.

b. Plot the graph of this function for 0≤x≤7

c. Explain what the slope and y-intercept mean for this function.

Answer 1

y = 5 * X + 25   

 

X           Y

-------------

0          25

1          30

2          35

3          40

4          45

5          50

6          55

7          60

 

slope is 5  :  price increases $5 for every gigabyte of data used

intercept is 25:   price begins at $25   (where line crosses y-axis)