Question

The following information is available.
 
H0 : μ ≥ 220
 
H1 : μ < 220
 
A sample of 64 observations is selected from a normal population. The sample mean is 215, and the population standard deviation is 15. Conduct the following test of hypothesis using the .025 significance level.
 
a.
Is this a one- or two-tailed test?
 
 
 

One-tailed test


 
b.
What is the decision rule? (Negative amount should be indicated by a minus sign. Round your answer to 2 decimal places.)
 
   H0 when z <    -2.00
 
c.
What is the value of the test statistic? (Negative amount should be indicated by a minus sign. Round your answer to 3 decimal places.)
 
  Value of the test statistic= ? I cannot not calculate this one I think it is 2.667, but it is wrong
 
 
d.
What is your decision regarding H0?
 
 
 

Reject


 
e.
What is the p-value? (Round your answer to 4 decimal places.)
 
  p-value=.0038
 
Accept H1 when z < 1.96

Z = (score-mean)/SEm

SEm = SD/√n

Z = (215-220)/(15/8) = -5/1.875 = -2.667

Agree with e.

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