Question

A tire company wants to know how quickly the tread on its tires wears down with average use. Have x represent the number of months the tire was used and have y represent the thickness of the tire tread, in millimeters. The equation for the line of best fit is:

y = -3/7x +20

1. What is the slope of the line? *
3/7
-3/7
20
-20

What does the slope represent for the tire company? *
The decrease of time (in months) the tires were used.
The increase of time (in months) the tires were used.
The tire tread decreases by this much each month.
The tire tread increases by this much each month.

2. What is the y-intercept of the line? *
3/7
-3/7
20
-20

What does the y-intercept represent for the tire company? *
How thick the tires were when they started.
The number of months they measured the tire tread.
The increase in tire tread.
The decrease in tire tread.

Answer 1

1) y=mx+b
m=slope
m=-3/7 in y=-3/7x+20

2) Since the slope is negative it is decreasing, as seen on a graph. So, the tire tread would be decreasing by the month (x).

3) y=mx+b
b=y-intercept
b=20 in y=-3/7x+20

Answer 2

1) m=-3/7 in y=-3/7x+20

2) not sure

3)b=20 in y=-3/7x+20