Question
A simple random sample of 40 recorded speeds (in mph) is obtained from cars traveling on...
A simple random sample of 40 recorded speeds (in mph) is obtained from cars traveling on a section of Highway 405 in Los Angeles. The sample has a mean of 68.4 mph and a standard deviation of 5.7 mph. Use a 0.05 level of significance to test the claim that the mean speed of all cars is greater that the posted speed limit of 65 mph
Homework Answers
Answer #1
H0: Null Hypothesis: 
65
HA: Alternative Hypothesis: 
> 65
SE = s/
= 5.7/
= 0.9012
Test statistisc is:
t = (
-
)/SE
= (68.4 - 65)/0.9012 = 3.7727
ndf = 40 - 1 = 39
= 0.05
One tail - right side test
From Table, critical value of t = 1.6849
Since the calculated value of t = 3.7727 is greater than critical value of t = 1.6849, Reject H0.
Conclusion:
The data support the claim that the mean speed of all cars is
greater than the posted speed limit of 65 mph.
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