A survey is being planned to determine the mean amount of time corporation executives watch television. A pilot survey indicated that the mean time per week is 15 hours, with a standard deviation of 3.5 hours. It is desired to estimate the mean viewing time within one-quarter hour. The 98 percent level of confidence is to be used.
How many executives should be surveyed?
Schadek Silkscreen Printing Inc. purchases plastic cups on which to print logos for sporting events, proms, birthdays, and other special occasions. Zack Schadek, the owner, received a large shipment this morning. To ensure the quality of the shipment, he selected a random sample of 300 cups. He found 15 to be defective.
(a) What is the estimated proportion defective in the population? (Round your answer to 2 decimal places.)
Estimated proportion defective ( )
(b) What are the endpoints of a 95 percent confidence interval for the proportion defective. (Round your answers to 3 decimal places.)
Endpoints ( , )
(c) Zack has an agreement with his supplier that he is to return lots that are 10 percent or more defective. Should he return this lot?
( )- no, lot not 10% defective
( )- yes, the lot is 10% defective
( )- yes 15 is outside the confidence interval
A sample of 12 observations is selected from a normal population for which the population standard deviation is known to be 4. The sample mean is 19. (Round your answers to 3 decimal places.)
(a) The standard error of the mean is [ ]
(c) The 90 percent confidence interval for the population mean is between [ ] and [ ] .
The owner of Britten's Egg Farm wants to estimate the mean number of eggs laid per chicken. A sample of 20 chickens shows they laid an average of 19 eggs per month with a standard deviation of 2.06 eggs per month.
(a-1) What is the value of the population mean?
19, 2.06, or unknown
(a-2) What is the best estimate of this value? [ ]
(c) For a 90 percent confidence interval, the value of t is [ ] . (Round your answer to 3 decimal places.)
(d) The 90 percent confidence interval for the population mean is [ ] to [ ] (Round your answers to 3 decimal places.)
(e-1) Would it be reasonable to conclude that the population mean is 22 eggs?
yes or no
(e-2) What about 24 eggs?
yes or no