Line of Best Fit Slope and Y Intercept

Which of the following situations could be descried by the equation y= -25x + 120

• There are 120 people in the football stadium, and 25 more are entering each hour.

• A plumber charges $25 for a house call and $120 per hour.

• A teacher has 120 students. Her third period has 25 students

• There are 120 gallons of water in a tank. It releases water at a rate of 25 gallons per minute

• The slope indicates an increase of $180 in selling price for each additional thousand miles driven.

• The slope represents a decrease of $180 in selling price for each additional thousand miles driven.

• The slope represents a decrease of $180 in selling price for every 17.72 miles driven.

• The slope shows that the selling price remains constant regardless of the mileage.

• The slope of 4.87 represents a total cost of $4,870 for any sailboat length.

• The slope of 4.87 indicates an increase of 4.87 feet of sailboat length for every $1000 increase in price.

• The slope of 4.87 indicates a decrease of $4,870 in cost for each additional foot of sailboat length.

• The slope of 4.87 represents an increase of $4,870 in cost for each additional foot of sailboat length.

The equation models the month, x, and ticket sales, y (in thousands) of movie tickets sold from January to June for a theater. In the equation, x = 1 represents January. Identify and interpret the slope in the context of the situation.

• slope=1.3; The theater's sales increase by $1,000 every 1.3 months.

• slope=1.3; The theater's sales increasing by about $1,300 every month.

• slope=27; The theater's sales increasing by about $27,000 every month.

• slope=27; The theater's sales increase by $1,000 every 27 months.

Suppose a LINE OF BEST FIT passes through the points (6, 34) and (8, 50). The EQUATION of this line is . . .? (hint: find the slope and the equation in point-slope form. THEN put it into slope-intercept form)

• y = 8x – 5

• y = 2x

• y = 2x + 7

• y = 8x – 14

Suppose data related to the AVERAGE Temperature outside (T) and the number of winter Coats (C) sold at a store is collected and graphed.

The LINE OF BEST FIT has the equation C = -3T + 150.

Use this equation to predict the number of coats sold when the average temperature outside is 20°.

• 40

• 75

• 90

• 115

Suppose a LINE OF BEST FIT passes through the points (4, 8) and (6, 2). The SLOPE of this line is . . .?

• -3

• -6

• 4

• 2

The Y-INTERCEPT of this line is . . .? (hint: find the equation in point-slope form first and then put it into slope-intercept form)

• 11

• 4

• 9

• 20

In the equation y=3x-5, what is the value of the y-intercept?

• 3

• -5

• -3/5

• -2

The equation of the line of best fit of a scatter plot is y = 6x − 9. What is the slope of the equation?

• -6

• -9

• 6

• 9