Question

2. The table shows distance, y, that Mario runs in x minutes.

Mario’s Running Speed
Time,
(min) Distance,
(mi)
7 1
21 3
35 5

(a) Based on the information in the table, write an equation that can be used to model the relationship between the time (x) and distance (y). Show your work.
(b) What is the rate of change for this linear relationship? Show your work.
(c) What is Mario’s distance given that he ran for 70 minutes? Show your work.

Answer 1

Equation: y = ⅐x

Rate of change: ⅐

Distance = 10 miles

Explanation:

Given

The information in the above table

Solving (a): The equation

To get the equation, we need to first calculate the slope (m)

Take any two corresponding values of x and y

(x1,y1) = (7,1)

(x2,y2) = (21,3)

m = (y2 - y1)/(x2 - x1)

m = (3 - 1)/(21 - 7)

m = 2/14

m = ⅐

The equation is calculated using

y - y1 = m(x - x1)

Substitute values for m, x1 and y1

y - 1 = ⅐(x - 7)

y - 1 = ⅐x - 1

Add 1 to both sides

y = ⅐x

Solving (b) Rate of change:

The calculated slope in (a) above represents the rate of change.

So:

Rate of change = Slope = ⅐

Solving (c): Distance when time is 70 minutes

This implies that x = 70

Substitute 70 for x in y = ⅐x

y = ⅐ * 70

y = 10 miles