Multiple Choice 18-20

1.What is the primary purpose of a 95% confidence interval for a mean?

A.to estimate a sample mean

B.to test a hypothesis about a sample mean

C.to estimate a population mean

D.to provide an interval that covers 95% of the individual values in the population

2.A researcher asked random samples of 50 kindergarten teachers and 50 12^th grade teachers how much money they spent out-of-pocket on school supplies in the previous school year, to see if teachers at one grade level spend more than the other. A 95% confidence interval for the difference m_K - m₁₂ is $30 to $50. Based on this result, it is reasonable to conclude that

A.95% of all kindergarten and 12^th grade teachers spend between $30 and $50 on average.

B.95% of all kindergarten teachers spend between $30 and $50 more then 95% of all 12th grade teachers.

C.kindergarten teachers spend more on average than do 12^th grade teachers.

D.12^th grade teachers spend more on average than do kindergarten teachers.

3.A null hypothesis is that the average pulse rate of adults is 70.For a sample of 64 adults, the average pulse rate is 71.8.A significance test is done and the p-value is 0.02.What is the most appropriate conclusion?

A.Conclude that the population average is 70.

B.Conclude that the population average is 71.8.

C.Reject the hypothesis that the population average is 70.

D.Reject the hypothesis that the sample average is 70.