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A random sample of 81 students at a local university showed that they work an average of 60 hours per month with a standard deviation of 18 hours. Compute a 95% confidence interval for the mean of t
After computing a confidence interval, the user believes the results are meaningless because the width of the interval is too large. Which one of the following is the best recommendation?
Using an a = 0.04 a confidence interval for a population proportion is determined to be 0.65 to 0.75. If the level of significance is decreased, the interval for the population proportion
A machine that produces a major part for an airplane engine is monitored closely. In the past, 10% of the parts produced would be defective. With a .95 probability, the sample size that needs to be
We are interested in conducting a study in order to determine what percentage of voters of a state would vote for the incumbent governor. What is the minimum size sample needed to estimate the popul
A random sample of 144 observations has a mean of 20, a median of 21, and a mode of 22. The population standard deviation is known to equal 4.8. The 95.44% confidence interval for the population mea
A random sample of 64 students at a university showed an average age of 25 years and a sample standard deviation of 2 years. The 98% confidence interval for the true average age of all students in t
A random sample of 49 statistics examinations was taken. The average score, in the sample, was 84 with a variance of 12.25. The 95% confidence interval for the average examination score of the popul
Assuming a population standard deviation of 6 hours, what is the required sample size if the error should be less than 1/2 hour with a 95% level of confidence?
Whenever the population standard deviation is unknown and the population has a normal or near-normal distribution, which distribution is used in developing an interval estimation?
From a population that is not normally distributed and whose standard deviation is not known, a sample of 6 items is selected to develop an interval estimate for the mean of the population (m).
A sample of 200 elements from a population with a known standard deviation is selected. For an interval estimation of m, the proper distribution to use is the:
An estimate of a population parameter that provides an interval of values believed to contain the value of the parameter is known as the:
A quality control technician is checking the weights of a product. She takes a random sample of 8 units and weighs each unit. The observed weights are shown below. Assume the population has a normal
In a poll of 600 voters in a campaign to eliminate non-returnable beverage containers, 210 of the voters were opposed. Develop a 92% confidence interval estimate for the proportion of all the voters
Assuming the standard deviation of the population is 1.28, determine the size of the sample.
In a random sample of 400 residents of Chattanooga, 320 residents indicated that they voted for the Democratic candidate in the last presidential election. Develop a 95% confidence interval estimate
Evaluate the decision alternatives open to the company using decision trees.Which alternative should be followed by the Planwell company and what return can be expected?
What size sample would be required to estimate the proportion of hospital referrals with a margin of error of 0.04 or less at 95% confidence?
The average score of a sample of 87 senior business majors at UTC who took the Graduate Management Admission Test was 510 with a standard deviation of 36. Provide a 98% confidence interval for the m
The manager of a grocery store wants to determine what proportion of people who enter his store are his regular customers. What size sample should he take so that at 97% confidence the margin of err
The monthly starting salaries of students who receive an MBA degree have a population standard deviation of $110. What size sample should be selected to obtain a 0.95 probability of estimating the m
A sample of 36 patients in a doctor's office showed that they had to wait an average of 45 minutes with a standard deviation of 10 minutes before they could see the doctor. Provide a 90% confidence
If the standard deviation of the lifetime of a vacuum cleaner is estimated to be 300 hours, how large of a sample must be taken in order to be 97% confident that the margin of error will not exceed
A coal company wants to determine a 95% confidence interval estimate for the average daily tonnage of coal that they mine. Assuming that the company reports that the standard deviation of daily outp