11. A manufacturer receives parts from two suppliers. An SRS of 400 parts from supplier I finds 20 defective. An SRS of 100 parts from supplier 2 finds 10 defective. Let pt and po be the proportion of all parts from suppliers I and 2, respectively, that are defective. A 95% confidence interval for p₁ - p₂is
(A) -.056±0.068.

(B) -.056±0.054.
(C) -.056±0.033.
(D) .056 ±0.033.

7.A consumer protection agency is com paring he work of two electrical contractors. The agency plans to inspect residences in which each of these contractors has done the wiring in order to estimate the d ifference in the proportions of residences that are electrically deficient. Suppose the proportions of residences with deficient work are expected to be about . 2 for both contractors. How many homes should be sampled in order to estimate the difference in proportions using a 90% confidence interval of width . 5? )”(A)(B) (C) (D)

8. The FDA is comparing the mean ea feine contents of two brands of cola. Independent random samples of 6-oz. cans of Heach brand were selected and the caffeine content of each can determined. The study provided the following summary information. Brand A Brand B Sample size 20 Variance 1.2 How many cans of each soda would need to be sampled in order to estimate the difference in the mean caffeine content to within 10 with 90% reliability? (A)(B)(C) (D)

9.Suppose an experiment utilizing a random block design has3 treatments and 8 blocks for a total of 24 observations. Assume that the total Sum of Squares for the response is SS(Total) =400. If the Sum of Squares for Treatments (SST) is 10% of SS(Total), and the Sum of Squares for Blocks (SSB) is 20% of SS (Total), find the F values for this experiment. (A) treatments: F = 1.64； blocks: F= 0.94 (B) treatments: F = 0.67； blocks: F= 0.50 I(C) treatments: F= 1.00； blocks: F= 0.57 (D) treatments: F= 8.57； blocks: F= 2.45 

10. Event A occurs with probability 0.3. If event A and B are disjoint then (A)(B)(C)(D)

12. In a particular game, a fair die is tossed. If the number of spots showing is either 4 or 5 you win $1； if the number of spots showing is 6 you win S4； and if the number of spots showing is 1, 2, or 3, you win nothing. Let X be the amount that you win. The expected value of X is (A) $0.00. (B) $1.00. (C) $2.50. (D) $4.00.

13.The scores of individual students on the American College Testing (ACT) Program composite college entrance examination have a normal distribution with mean 18.6 and standard deviation 6.0. At Northside High, 36 seniors take the test. If the scores at this school have the same distribution as national scores, what is the standard deviation of the sampling distribution of the average (sample mean) score for the 36 students? (A) 1.0 (B) 3.1 (C) 6.0 (D) 18.6 

14. The proportion of defective components that the electronics manufacturer receives from these two plants is(A) 0.014.(B) 0.015.(C) 0.016.(D) 0.018.

15.The proportion of nondefective components that the electronics manufacturer receives from these two plants is(A) 0.982.(B) 0.984.(C) 0.985.(D) 0.986.

16. If a component received by the manufacturer is defective, the probabil ity that it was produced at plant A is (A) 1/7.(B) 2/7.(C) 3/7.(D) 4/7.

 17. If a component received by the manufaeturer is not defective, the probability that it was produced at plant A is (A) 0.602. (B) 0.622. (C)0.684. (D) 0.713.