The Rocky Mountain district sales manager of Rath Publishing Inc., a college tex

Question

The Rocky Mountain district sales manager of Rath Publishing Inc., a college textbook publishing company, claims that the sales representatives make an average of 40 sales calls per week on professors. Several reps say that this estimate is too low. To investigate, a random sample of 28 sales representatives reveals that the mean number of calls made last week was 42. The standard deviation of the sample is 2.1 calls. Using the .05 significance level, can we conclude that the mean number of calls per salesperson per week is more than 40?

a What is the Null Hypothesis?

Ho µ _____ _____

Ha µ _____ _____

b Hypothesis test being performed is? (Circle answer) Left tail test, Right tail test Two tail test

c Degrees of freedom, df for the test statistic t is?

df = ________

d Numerical value of the test statistic t is? (Show work)

t = ________

e Method of calculation (Circle answer) Table, Computer algorithm

Pvalue = _______

f Your Decision is? (Circle answer) Null Hypothesis, Alternate Hypothesis, Insufficient information to make decision

Explanation / Answer

Answer to the question is as follows. Write back in case you have doubts:

a.

The claim is that 40 calls on average are made per week

Sample size, n = 28

Sample mean = 42

Standard dev of sample, s = 2.1

alpha = .05

Ho:Mu<=40

Ha:Mu>40

b.

Right tailed test

c. df = n-1 = 28-1 = 27

d. t = (Sample mean - Pop. mean)/(s/sqrt(n)) = (42-40)/(2.1/sqrt(27)) = 4.95

e. Now, calculate the P-value by df = n-1 = 27 at t = 4.95 to get :

The P-Value of .000017.

The result is significant at p < .05.

f. We will reject null hypothesis and conclude that the claim of the salesman is CORRECT

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