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Null Hypothesis

2)Your company has recently changed suppliers of a certain raw material in an effort to reduce the number of defective units being produced at your plant. During the past year, the sampling has indicated a daily mean of 21.2 defective units. After testing the new suppliers raw materials for 30 days, it was found that the mean during the trial period was 19.8 with a sample deviation of 5. Testing at the 5% level of significance, has the change in suppliers had the desired effect?

Complete the following

H0:  =

H1: 

Alpha =

St. error =

n =

sample mean =

Calculations leading to your conclusion:

Final answer:

6.How does changing the alpha value affect the width of the confidence interval?

7.How does increasing the sample size affect the width of the confidence interval?