Proportions

A realtor has been told that 43% of homeowners in a city prefer to have a finished basement. She surveys a group of 300 homeowners randomly chosen from her client list. Describe the sampling distribution model of the proportion of homeowners in this sample who prefer a finished basement.

• mean = 43%; standard deviation = 1.4%

• mean = 57%; standard deviation = 2.9%

• mean = 57%; standard deviation = 1.4%

• mean = 43%; standard deviation = 2.9%

• There is not enough information to describe the distribution.

According to government data, 22% of American children under the age of six live in households with incomes less than the official poverty level. A study of learning in early childhood chooses an SRS of 300 children.

Are the conditions/assumptions for normality met?

• Yes, all of them are met.

• No, the sample is not random

• No, we have less than 10 successes

• No, 300 is more than 10% of all children

A survey of 800 women shoppers found that 17% of them shop on impulse.  What is the 98% confidence interval for the true proportion of women shoppers who shop on impulse? 

• 0.148 < p < 0.192

• 0.136 < p < 0.204

• 0.144 < p < 0.196

• 0.139 < p < 0.201

The symbol for the sample proportion is __________.

• Z_c

• p̂

• E

• q

A research company wants to estimate the proportion of people who like oatmeal.  They want the confidence level to be 95%.  The company gets 325 people to sign up for the survey, but on the day that the survey is issued, only 250 people show up and take the survey.  What happens to the confidence interval?

• It gets larger

• It gets smaller

• It stays the same

• Too little information given

A sample of 400 racing cars showed that 80 cars cost over $700,000. What is the 99% confidence interval of the true proportion of cars costing over $700,000?

• 0.001 < p < 0.005

• 0.566 < p < 0.693

• 0.148 < p < 0.252

• 0.023 < p < 0.045

A recent study of 750 Internet users in Europe found that 35% of Internet users were women.  What is the 95% confidence interval of the true proportion of women in Europe who use the Internet? 

• 0.321 < p < 0.379

• 0.316 < p < 0.384

• 0.309 < p < 0.391

• 0.305 < p < 0.395

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

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