Inference for Proportions

Conduct a test to determine whether or not the population proportion of voters in favor of proposal A is greater than 50%. In a random sample of 200 voters, 140 said that they were in favor of this proposal. Compute the test statistic.

• z = 6.17

• z = 5.66

• z = 19.80

• None of the above

Which of the following hypotheses is a valid example of a 1-tailed test?

• Ho: p = 0.3, Ha: p > 0.4

• Ho: p = 0.3, Ha: p ≠ 0.3

• Ho: p^ = 0.3, Ha: p^ > 0.3

• Ho: p = 0.3, Ha: p > 0.3

Two confidence interval estimates from the same sample are (0.72, 0.83) and (0.75, 0.81). One is at 95%, the other is at 99%. Which is which?

• (0.72, 0.83) is at 99%

• (0.72, 0.83) is at 95% 

• Need to know sample size to determine this

• Need to know standard error to determine this

Tina wants to know if the proportion of people who buy burgers is at all affected by her open mic reading. If p=0.8 before her reading, what is an appropriate set of hypotheses?

• Ho: p = 0.8
  Ha: p > 0.8

• Ho: p = 0.8
  Ha: p < 0.8

• Ho: p ≠ 0.8
  Ha: p = 0.8

• Ho: p= 0.8
  Ha: p ≠ 0.8

A credit card company would like to compare the proportion of people who have poor credit to the proportion of people who think they have poor credit. Which of the following is most appropriate?

• Proportion Z-Test

• Proportion Z-Interval

• 2-Proportion Z-Test

• 2-Proportion Z-Interval

A 99% confidence interval found that the true proportion of teens who drink coffee every day is in the interval (0.785, 0.831). What was the p^ value used to determine this interval? 

• 0.8

• 0.808

• 0.825

• 0.831

Which of the following is true pertaining to a 2-proportion z-interval?

• There are no restrictions on sample size 

• This interval can be found even if the samples are not random

• The population should be large, relative to each of the sample sizes

• So long as all conditions are met for one sample, you do not need to check conditions for the other sample

In a past General Social Survey, a random sample of men and women answered the question “Are you a member of any sports clubs?” Based on the sample data, 95% confidence intervals for the population proportion who would answer “yes” are .13 to .19 for women and .247 to .33 for men. Based on these results, you can reasonably conclude that 

• At least 25% of American men and American women belong to sports clubs.

• At least 16% of American women belong to sports clubs. 

• There is a difference between the proportions of American men and American women who belong to sports clubs.

• There is no conclusive evidence of a gender difference in the proportion belonging to sports clubs

A test was conducted to see if there was evidence that more than 10% of the population is left-handed. Ho: p = 0.10, Ha: p >0.10. A p-value of 1.10 is found. What can we conclude?

• There is not evidence that more than 10% of people are left-handed

• We can conclude that more than 10% of people are left-handed

• There is evidence that more than 10% of people are left-handed

• The person who ran this test made an error

Which of the following is the most appropriate interval for the manager to use for such an estimate?

• A

• B

• C

• D

• E