The National Highway Association is studying the relationship between the number of bidders on a highway project and the winning (lowest) bid for the project. Of particular interest is whether the number of bidders increases or decreases the amount of the winning bid.

Project	Number of Bidders, X		Winning Bid ($ millions), Y	Project		Number of Bidders, X	Winning Bid ($ millions), Y
1	9		5.1	9		6	10.3
2	9		8.0	10		6	8.0
3	3		9.7	11		4	8.8
4	10		7.8	12		7	9.4
5	5		7.7	13		7	8.6
6	10		5.5	14		7	8.1
7	7		8.3	15		6	7.8
8	11		5.5

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Calculate the following from the table given above. (Negative values should be indicated by a minus sign. Round your answers to 2 decimal places.)

n
X
X2
Y
Y2
XY
syx
b
a

a-1.	Determine the regression equation. (Negative values should be indicated by a minus sign. Round your answers to 4 decimal places.)

yy^

=

+

X

a-2.	Choose the correct option.

More bidders tend to (Click to select) increase decrease the amount of the winning bid.

b.	Estimate the amount of the winning bid if there were seven bidders. (Round your answer to 4 decimal places.)

Estimated Amount

c.	A new entrance is to be constructed on the Ohio Turnpike. There are seven bidders on the project. Develop a 95% prediction interval for the winning bid. (Round your answers to 4 decimal places.)

The 95 percent prediction interval for the winning bid is up to .

d-1.	Determine the coefficient of determination. (Round your answer to 3 decimal places.)

Coefficient of determination

d-2.	The number of bidders explains nearly 50% of the variation in the amount of the bid. State True or False.
	multiple choice 2 False True

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