The weight of a car can influence the mileage that the car can obtain. A random...

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The weight of a car can influence the mileage that the car canobtain. A random sample of 20 cars’ weights and mileage iscollected. The table for the weight and mileage of the cars isgiven below. Use Excel to find the best fit linear regressionequation, where weight is the explanatory variable. Round the slopeand intercept to three decimal places.

Weight   Mileage
30.0   32.2
20.0   56.0
20.0   46.2
45.0   19.5
40.0   23.6
45.0   16.7
25.0   42.2
55.0   13.2
17.5   65.4
35.0   28.0
27.5   49.9
27.5   35.1
30.0   31.2
25.0   29.5
40.0   25.6
22.5   43.4
35.0   28.9
27.5   35.0
22.5   38.8
45.0   17.2

Answer & Explanation Solved by verified expert
3.6 Ratings (630 Votes)

Solution:

X

Y

X^2

Y^2

XY

30

32.2

900

1036.84

966

20

56

400

3136

1120

20

46.2

400

2134.44

924

45

19.5

2025

380.25

877.5

40

23.6

1600

556.96

944

45

16.7

2025

278.89

751.5

25

42.2

625

1780.84

1055

55

13.2

3025

174.24

726

17.5

65.4

306.25

4277.16

1144.5

35

28

1225

784

980

27.5

49.9

756.25

2490.01

1372.25

27.5

35.1

756.25

1232.01

965.25

30

31.2

900

973.44

936

25

29.5

625

870.25

737.5

40

25.6

1600

655.36

1024

22.5

43.4

506.25

1883.56

976.5

35

28.9

1225

835.21

1011.5

27.5

35

756.25

1225

962.5

22.5

38.8

506.25

1505.44

873

45

17.2

2025

295.84

774

635

677.6

22187.5

26505.74

19121


Regression equation can be calculated as
Y = a + bx
Here a is Y intercept and b is slope of regression line
Slope of line can be calculated as = (n*Summation(XY) - Summation(X)*Summation(Y)/ n*Summation(X^2) - (Summation(X))^2)
= (20*19121 - 635*677.6)/(20*22187.5-635*635) = -1.1809
Intercept can be calculated as
Intercept = Summation(Y) - b*Summation(X)/n = 677.6 - 635*(-1.18)/20 = 71.3736

So regression line is
Y = 71.3736 - 1.1809*X


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