Question

Math PT Question 19 Which of the following is the correct equation for the trend line in the scatter plot ?

Answer 1

Using the points where the blue line crosses the X and Y axis:

(0,5) ans (-1, 0)

The slope is the change in Y over the change in X:

0-5 / -1 - 0 = -5/-1 = 5

Slope = 5

Y intercept = y1 = 5

Equation = y = 5x+5

Answer 2

Answer:

The correct equation for the trend line is y = 5x + 5

Step-by-step explanation:

* Lets revise the form of the equation of the line

- The slope intercept form is y = mx + b, where m is the slope of  

  the line and b is the y-intercept

- In the problem we have a trend line in the scatter-plot

- we cant find the exact value of the slope of the line from the points

 in the scatter-plot because the line is best fit to the point, then we

 will start with the y-intercept of the line

- From the graph the line intersect the y-axis at point (0 , 5)

∴ The y-intercept is 5

- We have two answers have y- intercept = 5, the first and second

 answer, the right answer is one of them

- From the graph try to find two points closed the the line and use

 them to find the slope of the line

- There are two points approximately closed to the line at points

  (0 , 5) and (-1 , 0)

- Lets use the rule of the slope of a line which passes through points

  (x1 , y1) and (x2 , y2)

- The slope of the line = (y2 - y1)/(x2 - x1)

∵ The point (0 , 5) is (x1 , y1) and point (-1 , 0) is (x2 , y2)

∵ x1 = 0 , x2 = -1 and y1 = 5 , y2 = 0

∴ the slope = (0 - 5)/-1 - 0 = -5/-1 = 5

∵ The equation of the line is y = mx + b

∵ m = 5 and b = 5

∴ The equation is y = 5x + 5