Last year, during an investigation of the time spent reading e-mails on a daily basis,

researchers found that on Monday the average time was 50 minutes. Office workers claim that

with the increased spam and junk mail, this time has now increased. To conduct a test, a

sample of 25 employees is selected with the following results: sample mean = 51.05 minutes

and sample standard deviation = 14.2 minutes. What is the critical value for a = .05 to test the

hypotheses.

A. 1.711

B. 2.064

C. 2.060

D. 1.708

E. 1.645

A manufacturer of salad dressings uses machines to dispense liquid ingredients into

bottles that move along a filling line. The machine that dispenses dressing is working properly

when 8 ounces are dispensed. The standard deviation of the process is 0.15 ounces. A sample

of 48 bottles is selected periodically, and the filling line is stopped if there is evidence that the

mean amount dispensed is different from 8 ounces. Suppose that the mean amount dispensed

in a particular sample of 48 bottles is 7.983 ounces. Calculate a confidence interval to test the

hypotheses at a = .05.

A. [7.947 8.019]

B. [7.941 8.025]

C. [7.933 8.033]

D. [7.955 8.011]

E. [7.916 8.050]

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