1 .  1. A level C confidence interval is...

b .  an interval computed from sample data by a method that has probability C of producing an interval containing the true value of the parameter of interest

2 .  The upper .05 critical value of the standard normal distribution is...

b .  1.645

3 .  The upper .01 critical value of the standard normal distribution is...

c .  2.326

4 .  A sample of 25 seniors from a large metropolitan area school district had a mean Math SAT score of = 450. Suppose we know that the standard deviation of the population of Math SAT scores for seniors in the district is = 100. A 90% confidence interval for the mean Math SAT score µ for the population of seniors is... (Assume the population of Math SAT scores for seniors in the district is approximately normally distributed.)

a .  450 ± 32.9

5 .  A sample of 25 seniors from a large metropolitan area school district had a mean Math SAT score of = 450. Suppose we know that the standard deviation of the population of Math SAT scores for seniors in the district is = 100. A 90% confidence interval for the mean Math SAT score µ for the population of seniors is used. Which of the following would produce a confidence interval with a smaller margin of error?

a .  using a sample of 100 seniors

6 .  A sample of 25 seniors from a large metropolitan area school district had a mean Math SAT score of = 450. Suppose we know that the standard deviation of the population of Math SAT scores for seniors in the district is = 100. A 95% confidence interval for µ for the population of seniors with margin of error ± 25 is used. The smallest sample size we can take and achieve this margin of error is...

d .  62

7 .  The probability that a fixed significance level test will reject H₀ when a particular alternative value of the parameter is true is called ...

c .  power of the test against that alternative

8 .  The mean diameter µ of a certain bolt is supposed to be 1 centimeter (cm). Diameters of bolts vary normally with standard deviation = .01 cm. When a shipment of bolts arrive, an inspector takes a SRS of 25 bolts from the shipment and measures their diameters. The inspector rejects the shipment if the sample mean diameter differs from 1 cm by more than .005 cm. Notice that the inspector is testing the hypotheses: H₀: µ = 1 H_a: µ 1 What is the power of the test when µ = 1.005?

d .  .5

9 .  You have a SRS of size n = 9 from a normal distribution with = 1. You wish to test the hypotheses: H₀: µ = 0 H_a: µ >0. You decide to reject H₀ if >1. The probability of a Type I error is...

d .  .0013

10 .  You have a SRS of size n = 9 from a normal distribution with = 1. You wish to test the hypotheses: H₀: µ = 0 H_a: µ >0 You decide to reject H₀ if >1. What is the probability of a Type II error when µ = 1?

a .  .5

11 .  You have a SRS of size n = 9 from a normal distribution with = 1. You wish to test the hypotheses: H₀: µ = 0 H_a: µ >0 You decide to reject H₀ if >1. What is the power of the test when µ = 1?

b .  .5

12 .  In a test of hypotheses, we say that the data are statistically significant at level if

c .  the P-value is smaller than

13 .  In a test of hypotheses, if we insist on very strong evidence against the null hypothesis H₀ we should choose to be...

a .  very small

14 . 

A particular brand of paint advertises that a one gallon can covers at least 400 square feet. A consumer group tests the claim by purchasing a sample of 4 one gallon cans and measuring the number of square feet covered by each can. The distribution of the coverage for the population of all one gallon cans of paint of this brand is normal with standard deviation 20 square feet. The number of square feet covered by the sample of cans of paint is:

410 390 380 420

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a .  It is not statistically significant at = .10.

15 .  Using the above data (#14), what are the hypotheses being tested?

c .  H₀: µ = 400 and H_a: µ <400