Exam 8: Estimation of the Mean and Proportion

A researcher wants to make a 99% confidence interval for a population mean.She wants the margin of error to be within 4.6 of the population mean.The population standard deviation is 18.22.The sample size that will yield a margin of error within 4.6 of the population mean is:

In a random sample of 562 items produced by a machine,the quality control staff found 6.6% to be defective.Based on this sample,the 95% confidence interval for the proportion of defective items in all items produced by this machine,rounded to four decimal places,is:

Determine the sample size n that is required for estimating the population mean.The population standard deviation and the desired margin of error are specified. 94% margin of error 3 A)8,836 B)8,836 C)8,835 D)8,837

A researcher wants to make a 99% confidence interval for a population proportion.A preliminary sample produced the sample proportion of 0.680.The sample size that would limit the margin of error to be within 0.024 of the population proportion is:

An employee of the College Board analyzed the mathematics section of the SAT for 97 students and finds = 30.2 and s = 13.0.She reports that a 97% confidence interval for the mean number of correct answers is (27.336,33.064).Does the interval (27.336,33.064)cover the true mean? Which of the following alternatives is the best answer for the above question?

The correct formula for the limits of a confidence interval is:

A company wants to estimate,at a 95% confidence level,the proportion of all families who own its product.A preliminary sample showed that 30.0% of the families in this sample own this company's product.The sample size that would limit the margin of error to be within 0.045 of the population proportion is:

To decrease the width of a confidence interval,we should always prefer to:

For most distributions,we can use the normal distribution to make a confidence interval for a population mean provided that the population standard deviation is known and the sample size is:

The Labor Bureau wants to estimate,at a 90% confidence level,the proportion of all households that receive welfare.A preliminary sample showed that 18.5% of households in this sample receive welfare.The sample size that would limit the margin of error to be within 0.036 of the population proportion is:

The Labor Bureau wants to estimate,at a 90% confidence level,the proportion of all households that receive welfare.The most conservative estimate of the sample size that would limit the margin of error to be within 0.030 of the population proportion is:

A random sample of 765 persons showed that 13.5% do not have any health insurance.Based on this sample,the 95% confidence interval for the proportion of all persons who do not have any health insurance,rounded to four decimal places,is:

A random sample of 23 tourists who visited Hawaii this summer spent an average of $1,456.0 on this trip with a standard deviation of $263.00.Assuming that the money spent by all tourists who visit Hawaii has an approximate normal distribution,the 95% confidence interval for the average amount of money spent by all tourists who visit Hawaii,rounded to two decimal places,is:

A random sample of 983 families selected from a large city showed that 17.5% of them make $100,000 or more per year.Based on this sample,the 99% confidence interval for the proportion of all families living in this city who make $100,000 or more per year,rounded to four decimal places,is:

In a 1997 poll of 261 male,married,upper-level managers conducted by Joy Schneer and Frieda Reitman for Fortune magazine,31% of the men stated that their wives worked either full-time or part-time (Fortune,March 17,1997).What are the boundaries for a 99% confidence interval for p,the proportion of all male,married,upper-level managers whose wives work?

In a random sample of 53 items produced by a machine,the quality control staff found 5 of them to be defective.Calculate the point estimate of the population proportion of defective items.Round to 4 decimal places.

The z value for a 90% confidence interval for the population mean with known is:

True or False.The statement: "The 90% confidence interval for the mean is (29.83 ,50.1)." can be interpreted to mean that the probability that the mean lies in the range (29.83 ,50.1)is 90%.

The value of t for 19 degrees of freedom and a 98% confidence interval is:

A company wants to estimate the mean net weight of all 32-ounce packages of its Yummy Taste cookies at a 95% confidence level.The margin of error is to be within 0.025 ounces of the population mean.The population standard deviation is 0.096 ounces.The sample size that will yield a margin of error within 0.025 ounces of the population mean is: