Exam 9: Estimation and Confidence Intervals

Making generalized statements about a population based on sample information is called _________________.

In relative terms, a _______ confidence level leads to a narrower confidence interval.

The Nile Superstore is conducting a survey of consumer preferences for a new wireless e-book reader. A sample of 160 people reveals that 120 would buy the new reader. What is the 99% confidence interval for the population proportion?

The t distribution approaches the ____________ distribution as the sample size increases.

A research firm conducted a survey to determine the mean amount people spend at a popular coffee shop during a week. They found the amounts spent per week followed a normal distribution, with a population standard deviation of $4. A sample of 49 customers revealed that the mean is $25. What is the 95% confidence interval estimate of µ?

A silkscreen printing company purchases t-shirts. To ensure the quality of the shipment, 300 t-shirts are randomly selected. Fifteen are defective. What is the estimated proportion defective in the population?

A survey of 25 grocery stores revealed that the mean price of a gallon of milk was $2.98, with a standard error of $0.10. What is the 95% confidence interval to estimate the true cost of a gallon of milk?

Which of the following is a point estimate for the population mean (µ)?

To determine the value of the standard error of the mean, the standard deviation is divided by the sample size.

Knowing the population standard deviation, a 95% confidence interval infers that the population mean ___________.

A local company wants to evaluate their quality of service by surveying their customers. Their budget limits the number of surveys to 100. What is their maximum error of the estimated mean quality for a 95% level of confidence and an estimated standard deviation of 5?

A survey of 25 grocery stores revealed that the average price of a gallon of milk was $2.98, with a standard error of $0.10. What is the 98% confidence interval to estimate the true cost of a gallon of milk?

University officials say that at least 70% of the voting student population supports a fee increase. If the 95% confidence interval estimating the proportion of students supporting the fee increase is [0.75, 0.85], what conclusion can be drawn?

A point estimate is a single value used to estimate a population parameter.

A survey of households in a small town showed that in 500 of 1,200 sampled households, at least one member attended a town meeting during the year. Using the 95% level of confidence, what is the confidence interval for the proportion of households represented at a town meeting?

What kind of distribution is the t distribution?

Assuming a normal population with a known population standard deviation, the z statistic for a 90% confidence interval would be ____.

Sugar is packaged in 16-ounce bags. To test the weight of the bags, a few were checked. The mean weight was 15.95 ounces and the standard deviation was 0.5 ounces. How many bags must the processor sample to be 99% confident that the sample mean does not differ from the population mean by more than 0.2 ounces?

The probability that an interval estimate includes the population parameter is called the _____________.

To compute a confidence interval for a population proportion, a __________ statistic is used.