SOLUTION: The speed limit on I-25 in Colorado was raised to 75mph in certain sections in 2002. The speed of 144 cars passing a checkpoint in one of these sections was collected this year. It
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Question 1159076: The speed limit on I-25 in Colorado was raised to 75mph in certain sections in 2002. The speed of 144 cars passing a checkpoint in one of these sections was collected this year. It was found that the cars were traveling with a mean speed of 80mph with a standard deviation of 3mph.
Conduct a hypothesis test at α=0.05 level of significance to see if this is enough evidence to show that drivers are still speeding (more than 75mph) on these sections of highway.
What is the appropriate hypothesis?
Perform the test using either the critical value method or the p-value method.
State the conclusion of the test and interpret it. Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! Ho: speed 75 mph or less
Ha: speed > 75 mph
alpha=0.05 P{rejectHo|Ho true}
test is a t ((0.95,df=143) with a critical value of t>1.656
t=(x bar-mean)/s/sqrt(n)
=5*sqrt(144)/3
=20 highly significant for the speed being >75 mph with p value<< 0.0001
