The efficieny expert investigating the pit stop completion timescollected information from a sample of n = 50 trial run pit stopsand found the average time taken for these trials is 10.75 secs andthat the times varied by a standard deviation of s = 2.5secs.
Help the efficiency expert to test whether this shows evidence thatthe pit crew are completing the change in less than 12 secs,testing the hypotheses you selected in the previous question.
Complete the test by filling in the blanks in thefollowing:
- An estimate of the population mean is .
- The standard error is .
- The distribution is  (examples: normal / t12 /chisquare4 / F5,6).
The test statistic has value TS=Â Â .
Testing at significance level α = 0.05, the rejection regionis:
(less/greater) than  (2 decplaces).
Since the test statistic  (is in/is not in) therejection region, there (is evidence/is no evidence) toreject the null hypothesis, H 0.
There (is sufficient/is insufficient) evidence to suggestthat the average time taken for the pit crew to complete the pitstop, μ, is less than 12 .
Were any assumptions required in order for thisinference to be valid?
a: No - the Central Limit Theorem applies, which states thesampling distribution is normal for any populationdistribution.
b: Yes - the population distribution must be normallydistributed.
Insert your choice (a or b):
The test statistic has value TS=Â Â .
Testing at significance level α = 0.05, the rejection regionis:
(less/greater) than  (2 decplaces).
Since the test statistic  (is in/is not in) therejection region, there (is evidence/is no evidence) toreject the null hypothesis, H 0.
