Question

A computer technician charges $190 for a 3-hour appointment and $370 for a 7-hour appointment. Which of these represents a linear function that models the charge for hiring the technician for x hours?
A y = 55x + 190
B y = 55x + 45
C y = 45x + 190
D y = 45x + 55

Answer 1

Answer:

D. y = 45x + 55

Step-by-step explanation:

If a computer technician charges $190 for a 3-hour appointment and $370 for a 7-hour appointment, we can say that;

when c1 = $190, t1 = 3

when c2 = $370, t2 = 7

c is the amount charged

t is the time taken

First thug is to get the slope;

slope = c2-c1/t2-t1

slope = 370-190/7-3

slope = 180/4

slope = 45

Next is to get the intercept by substituting m = 45 and (190, 3) into the standard form of the equation y = mx+c as shown;

190 = 45(3)+c

190 = 135+c

c = 190-135

c = 55

Substitute into the standard form of the equation;

y = mx+c

y = 45x + 55

Hence option D is correct