Question

2. Determine slope and y-intercept for the regression equation ?

Suppose an environmental agency would like to investigate the relationship between the engine size of sedans and the miles per gallon (MPG) they get. The accompanying table shows the engine size in cubic liters and rated miles per gallon for a selection of sedans. Use this information to complete parts a through f. Click to view the table showing engine size and MPG for 9 car models. a. Construct a scatter plot for these data. Choose the correct graph below. O B. C. 32 1.9 1.9 Engine Sze Engine Size Table of Engine Size and MPG- Car Model A Model B Model C Model D Model E Model F Model G Model HH Model I Engine Size MPG 2.3 26 30 24 3.1 3.6 2.1 24 2.1 3.8 23 24 30

3. Provide an interpretation for the value of the slope?

4. Predict the MPG for a sedan with a 2.5-liter engine

5. Calculate the SST

6. Partition the SST into the SSR and the SSE

Answer 1

a) Scatter Plot: Option C) is correct

b)

3)

Find X Y and X as it was done in the table below 59.8 63 57.6 65.1 82.8 58.8 57.6 63 79.8 5.29 4.41 5.76 9.61 12.96 4.41 5.76 4.41 14.44 26 2.3 2.1 2.4 3.1 3.6 2.1 2.4 2.1 3.8 30 21 23 28 30 21 Find the sum of every column ΣΧ= 23.9, ΣΥ=227, ΣΧ.Y= 587,5, ΣΧ2-67.05 X , Y 587.5 Use the following equations to find a and b y_Y . y-Xs_ y-X-Σ XY 227 . 67.05-23.9-587.5 9.67.05-23.92 36.573 n-y XY _ Σ X . Σ Y 9-587.5-23.9-227 -4.274 n.ΣΧ2 _ (ΣΧ)2 9.67.05-(23.9)2 Substitute a and b in regression equation formula y=a+b-x y = 36.573-4.274-

Slope b1 = -4.274

As the unit change in Engine size, the MPG decreases by 4.274

4) When X = 2.5

$\widehat{Y} =36.573-4.274*2.5 =25.888$