Parking Tickets – A citizen’s group claims that the city of Cambridge issues an
ID: 2922889 • Letter: P
Question
Parking Tickets – A citizen’s group claims that the city of Cambridge issues an average of 60 parking tickets per day. The data below show the number of parking tickets issued each day for a randomly selected period of 30 days. Assume =13.42. State the null and alternate hypotheses, as well as the claim, which (hint!) is in the null hypothesis. Is there enough evidence to reject the group’s claim at = .05?
79 78 71 72 69 71 57 60
83 36 60 74 58 86 48 59
70 66 64 68 52 67 67
68 73 59 83 85 34 73
Explanation / Answer
n = 30
= 60
s = 13.42
x-bar = 66.33
Hypotheses:
Ho: = 60 [This is the claim]
Ha: 60
Decision Rule:
= 0.05
Lower Critical z- score = -1.959963985
Upper Critical z- score = 1.959963985
Reject Ho if |z| > 1.959963985
Test Statistic:
SE = s/n = 13.42/30 = 2.450145574
z = (x-bar - )/SE = (66.33 - 60)/2.45014557390644 = 2.583519962
p- value = 0.009779781
Since 0.00977 < 0.05, we reject Ho
There is sufficient evidence that 60