Researchers at the Mayo Clinic have studied the effect of sound levels on patient healing and have found a significant association (louder hospital ambient sound level is associated with slower postsurgical healing). Based on the Mayo Clinic's experience, Ardmore Hospital installed a new vinyl flooring that is supposed to reduce the mean sound level (decibels) in the hospital corridors. The sound level is measured at five randomly selected times in the main corridor.

New Flooring	Old Flooring
39	47
44	50
40	51
40	53
45	48

Click here for the Excel Data File (a-1) Does the evidence convince you that the mean sound level has been reduced? Select the appropriate hypotheses.

1. H₀: _{1 2} 0 vs. H₁: _{1 2} < 0
2. H₀: _{1 2} = 0 vs. H₁: _{1 2} 0
3. H₀: _{1 2} 0 vs. H₁: _{1 2} > 0

multiple choice 1

• a

• b

• c

(a-2) At = .05, what is the decision rule? Assume equal variances.

1. Reject the null hypothesis if t_calc > 1.86 (8 d.f.)
2. Reject the null hypothesis if t_calc < 1.86 (8 d.f.)

multiple choice 2

• a

• b

(a-3) Calculate the test statistic. (Round your answer to 4 decimal places. Input the answer as a positive value.)

(a-4) At = .05, is the mean sound level reduced?

(b-1) At = .05, has the variance changed? Choose the correct hypothesis.

1. H₀: ₁² / ₂² = 1 vs. H₁: ₁² / ₂² 1.
2. H₀: ₁² / ₂² 1 vs. H₁: ₁² / ₂² = 1.

multiple choice 3

• a

• b

(b-2) At = .05, what is the decision rule?

1. Reject H₀ if F_calc < 9.60 or F_calc > .1042. (d.f.₁ = 4, d.f.₂ = 4.)
2. Reject H₀ if F_calc > 9.60 or F_calc < .1042. (d.f.₁ = 4, d.f.₂ = 4.)

multiple choice 4

• a

• b

(b-3) What is the test statistic? (Round the test statistic value to 4 decimal places.)

(b-4) At = .05, has the variance changed?