Question

1. The 95% confidence interval states that 95% of the sample means of a specified sample size selected from a population will lie within plus and minus 1.96 standard deviations of the hypothesized population mean. T or F

2. Which of the following is NOT necessary to determine how large a sample to select from a population?

Multiple Choice

• The level of confidence in estimating the population parameter

• The size of the population

• The maximum allowable error in estimating the population parameter

• An estimate of the population variation

3.

A university surveyed recent graduates of the English department about their starting salaries. Four hundred graduates returned the survey. The average salary was $25,000. Assume for purposes of this problem that the population standard deviation is known, and it is $2,500. What is the 95% confidence interval for the mean salary of all graduates from the English department?

Multiple Choice

• $22,500 and $27,500

• $24,755 and $25,245

• $24,988 and $25,012

• $24,600 and $25,600

4.

If 95% and 98% confidence intervals were calculated from the same sample data in order to estimate the true cost of an appliance with a known population standard deviation, what differences would there be between them?

Multiple Choice

• The standard errors would be different.

• The point estimates of the population mean would be different.

• The sample sizes would be different.

• The z-statistics would be different.

5.

A student wanted to construct a 95% confidence interval for the mean age of students in her statistics class. She randomly selected nine students. Their average age was 19.1 years with a sample standard deviation of 1.5 years. What is the best point estimate for the population mean?

Multiple Choice

• 2.1 years

• 1.5 years

• 19.1 years

• 9 years

Answer 1