Faced with rising fax costs, a firm issued a guideline that transmissions of 9 p
ID: 2923345 • Letter: F
Question
Faced with rising fax costs, a firm issued a guideline that transmissions of 9 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 9 or below. The firm examined 40 randomly chosen fax transmissions during the next year, yielding a sample mean of 10.47 with a standard deviation of 3.63 pages.
Find the test statistic. (Round your answer to 4 decimal places.)
At the .01 level of significance, is the true mean greater than 9?
Use Excel to find the right-tail p-value. (Round your answer to 4 decimal places.)
Faced with rising fax costs, a firm issued a guideline that transmissions of 9 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 9 or below. The firm examined 40 randomly chosen fax transmissions during the next year, yielding a sample mean of 10.47 with a standard deviation of 3.63 pages.
Explanation / Answer
xbar = 10.47
sd = 3.63
n = 40
mu = 9
t = (xbar-mu)/(sd/sqrt(n))
t = (10.47-9)/(3.63/sqrt(40)) = 2.56 is the test statistic
also df = n-1 = 40-1 = 39 ,
we check the p value in the t table for alpha = 0.01 and df = 39
WHICH IS 2.42 for 1 tail test
The exact p value from excel is 0.007227789
The excel formula is
=T.DIST.RT(2.56,39) , 39 is degree of freedom and 2.56 is the t stat we calculated above
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.