Question

Willa says the slope of the graph is -1/3.What error did she make?​

Answer 1

She counted the squares instead of using the scale.

Explanation:

I did the test

Answer 2

She counted the squares instead of using the scale.

EXPLANATION

The slope of a line is calculated using the formula

`m = (rise)/(run)`

This is the same as:

`m = (y_2-y_1)/(x_2-x_1)`

The given straight line passes through:

(4,24) and (16,18).

We plug in the values to obtain,

`m = (18 - 24)/(16 - 4)`

`m = ( - 6)/(12)`

`m = - ( 1)/(2)`

This is the correct expression for the slope.

But Willa mistakenly counted the squares instead of using the scale and had

`m = - (1)/(3)`

Each box on the y-axis is 3 units and each box on the x-axis is 2 units.

The rise is one box along the y-axis which is equal to 3 units the run is 3 boxes which is equal to 6 units.

The line has a negative slope.

Because she just counted the boxes and did use the scale, she got a wrong answer.