Question

Choose the correct response.

1. What should be your response to 737 respondents to a USA Today poll question on its Web site in which 92% said they do not open unfamiliar e-mail or instant message links?  Use a 0.01 significance level to test the claim that more than75% of us do not open unfamiliar messages.  
   1. Since the test statistic (z_cal) of 10.65 is greater than the critical value of 2.33 we would reject the null hypothesis and fully support the claim that more than 75% don’t open unfamiliar messages.
   2. Since the results are based on a voluntary response sample, the results are not necessarily valid and should not be relied upon.
   3. A significance level of 0.01 is excessive for simply measuring validity of opinions.  The more appropriate significance level of 0.05 would have resulted in a proper assessment of this problem.
   4. We would fail to reject the null hypothesis and concluded that 75% of us don’t open unfamiliar emails or instant messages.
2. A house cleaning service claims that it can clean a four-bedroom house in less than 2 hours. A sample of n = 36 houses is taken and the sample mean is found to be 1.97 hours and the sample standard deviation is found to be 0.1 hours. Using a 0.05 level of significance the correct conclusion is:
   1. a) reject the null because the test statistic (-1.8) is < the critical value (-1.64).
   2. b) do not reject the null because the test statistic (-1.8) is < the critical value (- 1.64).
   3. c) reject the null because the test statistic (-1.8) is > the critical value (-1.96).
   4. d) do not reject the null because the test statistic (-1.8) is > the critical value (- 1.96).
3. When testing a hypothesis, the hypothesis that is assumed to be true is
   1. the alternative hypothesis.
   2. neither the null or the alternative until the evidence supports one or the other.
   3. the null or the alternative.
   4. the null hypothesis.
4. Which statement is NOT true about hypothesis tests?
   1. a) Hypothesis tests are only valid when the sample is representative of the population for the question of interest.
   2. b) Hypotheses are statements about the population represented by the samples.
   3. c) Hypotheses are statements about the sample (or samples) from the population.
   4. d) Conclusions are statements about the population represented by the samples.
5. Suppose a 95% confidence interval for the proportion of Americans who exercise regularly is 0.29 to 0.37. Which one of the following statements is FALSE?
   1. It is reasonable to say that more than 25% of Americans exercise regularly.
   2. It is reasonable to say that more than 40% of Americans exercise regularly.
   3. The hypothesis that 33% of Americans exercise regularly cannot be rejected.
   4. It is reasonable to say that fewer than 40% of Americans exercise regularly.
6. Null and alternative hypotheses are statements about:
   1. population parameters.
   2. sample parameters.
   3. sample statistics.
   4. it depends - sometimes population parameters and sometimes sample statistics.
7. Which of the following is not a correct way to state a null hypothesis?
   1. H₀: µ = 0
   2. H₀: µ < 10
   3. H₀: µ ≥ 0
   4. H₀: µ ≤ .5
8. Which of the following shows a right-tailed test?
   1. H₁: µ < 15
   2. H₀: µ < 15
   3. H₁: µ > 15
   4. H₀: µ > 15
9. Which of the following shows a left-tailed test?
   1. H₁: µ < 15
   2. H₀: µ >15
   3. H₁: µ > 15
   4. H₀: µ > 15

Answer 1