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1. The city of Methods\' police department suspects that drivers are over speedi

ID: 3067811 • Letter: 1

Question

1.    The city of Methods' police department suspects that drivers are over speeding on Highway One, which has a posted speed limit of 60 mph. They decided to check this suspicions by monitoring drivers on the highway during a typical rush hour. The department considers a speed limit up to 65 mph acceptable, anything above 65 mph is unacceptable. Below are representative sample data collected during the rush hour monitoring:

75, 93, 66, 68, 60, 65, 63, 85, 78, 86, 73, 77, 69, 63, 64, 87, 93, 61, 80, 65, 82, 75, 60, 64, 62, 84, 64, 63, 63, 61, 70, 67, 76, 73, 72, 91, 80, 70, 89 and 82.

a.    (20 Points) Using a class interval (range) of "Below 65; 66 - 70; 71 - 75; 76 - 80; 81 - 85; 86 - 90; and 91 and above" complete the frequency distribution table below:

Class Interval

Frequency

Percentage

Cumulative Frequency

Up to 65

66 - 70

71 - 75

76 - 80

81 - 85

86 - 90

91 and above

Total

b.    (5 Points) Assuming that the dataset is from a representative sample, should the police department be concerned about speeding on Highway One? Justify your response.

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Explanation / Answer

(a)

Following is the completed table:

(b)

Yes because only 35% drive below or at 65 mph. That is more than 50% cross the speed limit. So  police department should be concerned about speeding on Highway One.

Class Interval Frequency , f Percentage , (f/40)*100% Cumulative Frequency Up to 65 14 35 14 66-70 6 15 20 71-75 5 12.5 25 76-80 5 12.5 30 81-85 4 10 34 86-90 3 7.5 37 91 and above 3 7.5 40 Total 40 100