Question

16. In April, Harry received his phone bill and found that he was charged $40 for 120
minutes of talking. In May, Harry received his phone bill and found that he was
charged $50 for 140 minutes of talking
Part A: Find the rate that Henry is charged for each minute of use.
a. $2 per minute
b. $1 per minute
C. $5 per minute
d. $0.50 per minute
Part B: Describe an equation in point slope form for calculating the cost (y) based on
minutes of use (x)

Answer 1

Step-by-step explanation:

A. Take two pairs of points:

• (120, 40) and (140, 50)

Find the rate of change:

• (50 - 40)/(140 - 120) = 10/20 = 0.5

This is the rate, $0.50 per minute

B. Take one pair of points (120, 40) to show the relationship between number of minutes and the cost:

• y - 40 = 0.5(x - 120)