A consulting psychologist is consulting with X-Bookstore to monitor customer com

Question

A consulting psychologist is consulting with X-Bookstore to monitor customer complaints. The national average for all bookstores is 6 complaints per month. Nine branches of X-Bookstore have been randomly selected to determine whether X-Bookstore has a different average number of complaints than bookstores in general. The average number of complaints from these 9 branches of X-Bookstore was calculated as 5 with the standard deviation of 3. Using .05 level of significance, what should the psychologist conclude?

a. Reject the null; X-Bookstore has significantly higher complaints than bookstores in general

b. Reject the null; There is no significant difference between the complaints received from X-bookstore and bookstores in general

c. Fail to reject the null; X-Bookstore has significantly higher complaints than bookstores in general

d. Fail to reject the null; There is no significant difference between the complaints received from X-bookstore and bookstores in general

Explanation / Answer

Ans:

Given that

sample mean=5

sample standard eviation=3

sample size=9

standard error of mean=3/sqrt(9)=1

Test statostic:

t=(5-6)/1=-1

df=8

p-value=tdist(1,8,2)=0.3466

As,p-value>0.05, Fail to reject the null; There is no significant difference between the complaints received from X-bookstore and bookstores in general

Option d is correct.

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