Questions 21-24 refer to the following situation:

On his morning commute, a researcher notices that the shorter the interval of time between traffic light changes, the more vehicles run the red light. Interested in this relationship, the researcher conducts an experiment over the next few weeks. Each morning he first chooses a traffic light at random. Once the light changes, he begins counting the number of vehicles running red lights. He continues to count until the light changes again. The data on six lights is as follows:

Length of Light (X)   Number of Cars (Y)

10                 20

13                 19

19                 17

25                 11

28                 9

30                 8

21. Calculate the regression line.

22. What is the Y-intercept?

23. Calculate the coefficient of determination.

24. ""If the length of a light was 7 seconds, how many cars would you predict would run the red light?""

Use the following scenario for 25 only.

Use the method of regression analysis to test the relationship between temperature (X) and the number of cars recorded as speeding (Y). Set α = .05

Temperature   Number of Cars Speeding

50                  10

65  12

80  16

85  16

90  13

70  10

75  12

25. Use the method of regression analysis to test the relationship between temperature (X) and the number of cars reordered as speeding (Y). Set __=.05