Exam 8: Large-Sample Estimation

One-sided confidence bounds can be constructed for the population mean and population proportion p, but not for the difference between population means, or the difference between population proportions.

A social worker was interested in determining whether there is a significant difference in the average monthly cost per child for childcare outside the home between state supported facilities and privately owned facilities. Two independent random samples were selected yielding the following information: Find a 90% confidence interval for the true difference in average monthly cost of the childcare. ______________ Based on the interval above, can one conclude there is a significant difference in average cost of childcare between the state supported facilities and privately owned facilities? ______________ Explain. ________________________________________________________

A lawn service owner is testing new weed killers. He discovers that a particular weed killer is effective 89% of the time. Suppose that this estimate was based on a random sample of 60 applications. Construct a 90% confidence interval for p, the true proportion of weeds killed by this particular brand. ______________

The process of inferring the values of unknown population parameters from those of known sample statistics is called estimation.

Which of the following is not a part of the formula for constructing a confidence interval estimate of the population proportion?

Which of the following best defines an interval estimate?

Suppose a 90% confidence interval for the mean time it takes to serve a customer at a drive-in bank is 120 seconds to 220 seconds. At the 90% confidence level, there is not enough evidence to conclude that the mean service time is not 200 seconds.

The sample proportion is an unbiased estimator of the population proportion p.

A point estimate is an estimate of a population parameter, expressed as a single numerical value.

A childcare agency was interested in examining the amount that families pay per child per month for childcare outside the home. A random sample of 64 families was selected and the mean and standard deviation were computed to be $675 and $80, respectively. Find a 95% upper confidence bound for the true average amount spent per child per month on childcare outside the home. ______________

A statistician wishes to reduce the margin of error associated with a confidence interval estimate for a population proportion p. She needs to:

A 95% confidence interval for the population proportion p is found to be between .214 and .336. Based on this information, the sample proportion that generated the confidence interval was .122.

The mean of the sampling distribution of , the difference between sample proportions, is the difference between population proportions.