Explore BrainMass

Hypothesis Testing of Mean

A national sales manager of an automobile supply chain claims that monthly sales of auto parts at on of the district office are an average of $5,285. The district manager believes the amount is too high. They authorize you to settle the dispute. You take a simple random sample (n=25) of the sales receipts over the last three years. Upon reviewing the sales receipts, you determine that the mean sales are $4,720 with a standard deviation of $350. Test the national managers claim that the mean is actually less than $5,285 or more versus the district managers claim that the mean is actually less than $5,285. You may assume a=0.05 and the population is symmetric and mounded.
a) H0: Ha:
b)what is the critical value of the test statistic?
c)what is the calculated value of the test statistic?
d)what is the p-value of the test statistic?
e)make a diagram and shade the rejection region(s)
f) state and support your decision about the null hypothesis
g) construct a 95% confidence interval for the mean cost of the supplies.
h)what would you tell the national and district managers about their dispute?


Solution Summary

The solution provides step by step method for the calculation of testing of hypothesis. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.