Question

Given are five observations collected in a regression study on two variables.

xi	2	6	9	13	20
yi	9	18	8	25	21

(a)

Develop a scatter diagram for these data.

A scatter diagram has 5 points plotted on it. The horizontal axis ranges from 0 to 25 and is labeled: x. The vertical axis ranges from 0 to 30 and is labeled: y. The points are plotted from left to right in a downward, diagonal direction starting in the upper left corner of the diagram. The points are between 8 to 25 on the vertical axis and are fairly spread out.

A scatter diagram has 5 points plotted on it. The horizontal axis ranges from 0 to 25 and is labeled: x. The vertical axis ranges from 0 to 30 and is labeled: y. The points are plotted from left to right in an upward, diagonal direction starting in the lower left corner of the diagram. The points are between 5 to 22 on the vertical axis and are fairly spread out.

A scatter diagram has 5 points plotted on it. The horizontal axis ranges from 0 to 25 and is labeled: x. The vertical axis ranges from 0 to 30 and is labeled: y. The points are plotted from left to right in an upward, diagonal direction starting in the lower left corner of the diagram. The points are between 8 to 25 on the vertical axis and are fairly spread out.

A scatter diagram has 5 points plotted on it. The horizontal axis ranges from 0 to 25 and is labeled: x. The vertical axis ranges from 0 to 30 and is labeled: y. The points are plotted from left to right starting in the upper left corner of the diagram. Moving from left to right, the first 3 points appear to be plotted in an upward diagonal, direction while the next 2 points are much lower on the diagram.

(b)

Develop the estimated regression equation for these data.

ŷ =

(c)

Use the estimated regression equation to predict the value of y when

x = 9.

Answer 1

The statistical software output for this problem is:

Hence,

a) Scatterplot: Option C is correct.

b) Regression equation:

ŷ = 9.2 + 0.7x

c) Predicted value = 9.2 + 0.7*9 = 15.5