A graph titled Monthly Sales and Advertising Costs has Advertising Costs (1,000 dollars) on the x-axis and sales (1,000 dollars) on the y-axis. A line goes through points (6.4, 117) and (6.6, 120).

Question

The scatterplot and trend line show a positive correlation between advertising costs and sales.

Which two points can be used to find the slope of the trend line?

Point 1:
Point 2:

Answer 1

To find the slope of the trend line, you can use the two points that are on the line. The points provided in your description are:

• Point 1: (6.4, 117)
• Point 2: (6.6, 120)

You would use these two points to calculate the slope of the trend line. The slope (m) can be calculated using the formula:

\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]

Substituting in the values from the points:

• \( (x_1, y_1) = (6.4, 117) \)
• \( (x_2, y_2) = (6.6, 120) \)

You can now calculate:

• \( y_2 - y_1 = 120 - 117 = 3 \)
• \( x_2 - x_1 = 6.6 - 6.4 = 0.2 \)

Thus, the slope is:

\[ m = \frac{3}{0.2} = 15 \]

So, the two points you can use to find the slope of the trend line are:

Point 1: (6.4, 117)
Point 2: (6.6, 120)