Question

6.Suppose we have a two-tailed hypothesis test about µ conducted at α = 0.05. If the sample size is n = 3, what is the correct rejection region? a.z < -1.960 or z > 1.960 b. t > -2.920 c. t < 2.920 d. t < -4.303 or t > 4.303

7.The BAC levels for a bunch of amateur stage magicians were measured. The same thing for professional magicians! Both distributions are shown below. Which of the following best describes the relationship between center and spread for the two groups of magicians? A. µAmateur > µProfessional & σAmateur < σProfessional B. µAmateur < µProfessional & σAmateur > σProfessional C. µAmateur > µProfessional & σAmateur > σProfessional D.µAmateur < µProfessional & σAmateur < σProfessional

8.A group of 36 randomly selected Eminem fans has a mean age of 13 years and a standard deviation of 3 years. Which of the following is the correct 95% confidence interval and conclusion? A.We are 95% confident the true mean age of all Eminem fans is between 11.71 years and 14.29 years. B. We are 95% confident the true mean age of all Eminem fans is between 12.02 years and 13.97 years. C.We are 95% confident the sample mean age of Eminem fans is between 12.18 years and 13.82 years. D.We are 95% confident the sample mean age of Eminem fans is between 12.38 years and 13.47 years.

9.In a lab experiment with highly compensated volunteers, a random sample of 10 UF students (population 1) and a random sample of 10 USF students (population 2) were tested by Dr. Psycho Stevens to determine the time it took each to start crying after being stung by the RIFA (red imported fire ant). If Dr. Psycho Stevens wanted to test the hypothesis that USF took longer, which set of hypotheses would they use? From the answer choices provided, select the best one. A.H0: µ1-µ2 ≠ 0 vs. Ha: µ1-µ2 = 0 B.H0: µ1-µ2 = 0 vs. Ha: µ1-µ2 ≠ 0 C. H0: µ1-µ2 = 0 vs. Ha: µ1-µ2 < 0 D. H0: µ1-µ2 = 0 vs. Ha: µ1-µ2 > 0

10.The body weight of adult Greyhounds (Danny's mom's favorite dog) are mound-shaped and symmetric with a mean of 72 pounds and a standard deviation of 12 pounds. What percentage of these dogs weigh more than 36 pounds but less than 60 pounds? A.At least 25% B.Approximately 2.5% C. Approximately 16% D. At most 25%

Answer 1

6.

df = n-1 = 2

Critical value :

Two tailed critical value, t-crit = T.INV.2T(0.05, 2) = 4.303

Reject Ho if t < -4.303 or if t > 4.303

answer D.

7.

answer D. µAmateur < µProfessional & σAmateur < σProfessional

8.

x̅ = 13, σ = 3, n = 36

95% Confidence interval :

At α = 0.05 two tailed critical value, z_c = ABS(NORM.S.INV(0.05/2)) = 1.960

Lower Bound = x̅ - z_c*σ/√n = 13 - 1.96 * 3/√36 = 12.02

Upper Bound = x̅ + z_c*σ/√n = 13 + 1.96 * 3/√36 = 13.97

Answer: B. We are 95% confident the true mean age of all Eminem fans is between 12.02 years and 13.97 years.

9.

Answer: C. H0: µ1-µ2 = 0 vs. Ha: µ1-µ2 < 0

10.

µ = 72, σ = 12

P(36 < X < 60) =

= P( (36-72)/12 < (X-µ)/σ < (60-72)/12 )

= P(-3 < z < -1)

= P(z < -1) - P(z < -3)

Using excel function:

= NORM.S.DIST(-1, 1) - NORM.S.DIST(-3, 1)

= 0.1573 = 16%

Answer: C. Approximately 16%