Answer:
a)
: t=13 seconds
: t<13 seconds
b) At α= 0.01, one-tailed critical value is -2.33
c) Test statistic is −2,98
d) since -2.98<-2.33, we can reject the null hypothesis. There is significant evidence that mean pit stop time for the pit crew is less than 13 seconds at α= 0.01.
Step-by-step explanation:
according to the web search, the question is missing some words, one part should be like this:
"A pit crew claims that its mean pit stop time ( for 4 new tires and fuel) is less than 13 seconds."
Let t be the mean pit stop time of the pit crew.
: t=13 seconds
: t<13 seconds
At α= 0.01, one-tailed critical value is -2.33
Test statistic can be calculated using the equation:
where
- X is the sample mean pit stop time (12.9 sec)
- M is the mean pit stop time assumed under null hypothesis (13 sec)
- s is the population standard deviation (0.19 sec.)
- N is the sample size (32)
Then
≈ −2,98
since -2.98<-2.33, we can reject the null hypothesis. There is significant evidence that mean pit stop time for the pit crew is less than 13 seconds at α= 0.01.