Quiz 4

1.The mean diastolic blood pressure for a random sample of 70 people was 88 millimeters of mercury. If the standard deviation of individual blood pressure readings is known to be 9 millimeters of mercury, find a 90% confidence interval for the true mean diastolic blood pressure of all people.Round your answers to one decimal place.Then complete the table below: 
 

What is the lower limit of the 90% confidence interval?
What is the upper limit of the 90% confidence interval? 
 

2.Consider a t distribution with 16 degrees of freedom. Compute P(-1.47 < t < 1.47). Round your answer to at least three decimal places. 
 

Consider a t distribution with 21 degrees of freedom. Find the value of c such that P(t≤c) = 0.10. Round your answer to at least three decimal places. 
 

P(-1.47 < t < 1.47)= 
c = 
 

4.An automobile assembly line operation has a scheduled mean completion time,u , of 14.8 minutes. The standard deviation of completion times is 1.4 minutes. It is claimed that, under new management, the mean completion time has decreased. To test this claim, a random sample of 50 completion times under new management was taken. The sample had a mean of 14.3 minutes. Can we support, at the 0.01 level of significance, the claim that the mean completion time has decreased under new management? Assume that the standard deviation of completion times has not changed. 
Perform a one-tailed test. 
 

H0:
 

H1:
 

The type of Test statistic =
 

The value of the test statistic=
(Round to at least three decimial places)
 

The critical value at the 0.01 level of significance:(Round to at least three decimial places)
 

Can we support,the claim that the mean completion time has decreased under new management?