1.

Question

Are there more broken bones in summer or winter? We get records about the number of fractures treated in January and July at a random sample of 25 emergency rooms.

The 95% confidence interval for the mean change ( μd = μJan - μJuly )in the numbers of fractures between January and July is (-2, 4)

Interpret the confidence interval.


A) We are 95% confident that there are fewer fractures treated in July than January.
B) We are 95% confident that the mean change in fractures treated between July and January was between 2 fewer and 4 more fractures treated.
C) We are 95% confident that each emergency room treats between 2 fewer and 4 more fractures when comparing July to January.
D) We are 95% confident that the mean change in fractures treated between January and July was between 2 fewer and 4 more fractures treated.

2.
Every year Educational Services (ETS) selects readers for the Advanced Placement Exams. Recently the AP Statistics exam has been graded in Lincoln, Nebraska. One objective of ETS is to achieve equity in grading by inviting teachers to be readers from all parts of the nation. However budgets are a constant issue also. The accountants at ETS wonder if the flights from cities west of Lincoln are the same as flight costs from cities east of Lincoln. A random sample of the expense vouchers from last year was reviewed for the cost of airline tickets.

Identify the null and alternative hypotheses.

A.
μEast - μWest ≠ 0

B.
μEast - μWest = 0

C.
μEast - μWest < 0

D.
μEast - μWest > 0

H0: (what letter)
HA: (what letter)

3.

Researchers developing new drugs must be concerned about possible side effects. They must check a new medication for arthritis to be sure that it does not cause an unsafe increase in blood pressure. They measure the blood pressures of a group of 12 subjects, then administer the drug and recheck the blood pressures one hour later.

Identify the null and alternative hypotheses.


A.
μAfter - μBefore > 0

B.
μAfter - μBefore < 0

C.
μd < 0 where μd = μAfter - μBefore

D.
μA - μB ≠ 0

E.
μd > 0 where μd = μAfter - μBefore

F.
μd = 0 where μd = μAfter - μBefore

G.
μAfter - μBefore = 0

H.
μd ≠ 0 where μd = μAfter - μBefore

H0: (what letter)
HA: (what letter)

Thank you!