AP Statistics Inference for Proportions

In a survey of 104 students, it was found that 79 went to the homecoming game this year. A 99% confidence interval for p is (0.652, 0.868). Interpret this interval.

• 99% of the time the true proportion of people who went to the homecoming game this year is between 65.2% and 86.6%.

• The probability that the population proportion of people who went to the homecoming game this year is between 65.2% and 86.6% is 95%.

• Based on this sample, I am 99% confident that the true proportion of people who went to the homecoming game this year is between 65.2% and 86.6%.

• 99% of all possible intervals calculated this way will capture the true proportion of people who went to the homecoming game this year

A preliminary study suggests that 17% of people agree on an issue. How large must your sample size be so you could be within ± 5% with 95% confidence?

• 217

• 30

• 2

• 152

A random sample of 100 WHS students found that 53 of them were in possession of a pencil. What is the p-hat for this sample?

• 0.53

• 0.5

• 0.47

• 1

In a survey of 104 students, it was found that 79 went to the homecoming game this year. Calculate a 99% confidence interval for p.

• (0.652, 0.868)

• (0.691, 0.829)

• (0.678, 0.842(

• (0.685, 0.895)

Kiley has a dime and a nickel, and she wonders if they have the same likelihood of showing heads when they are flipped. She flips each coin 100 times to test if there is a significant difference in the proportion of flips that they each land showing heads.

Which of the following is an appropriate set of hypotheses for Kiley's significance test?

• 
• 
• 
• 

Elsie bought a new bowling ball. She suspects that she'll roll a strike in a larger percentage of rolls with her new ball than her old ball. She takes a sample of 50 rolls with each ball to test if she rolls a strike significantly more often with the new ball.

Which of the following is an appropriate set of hypotheses for Elsie's significance test?

• 
• 
• 
• 

If the difference of two proportions (p₁-p₂) shows a confidence interval of (-0.13, 0.32), what would have been our decision from the 2-prop z-test?

• Fail to reject Ha since 0 is in the interval

• Fail to reject Ho since 0 is in the interval

• Reject Ho since 0 is in the interval

• Reject Ha since 0 is in the interval

What does this symbol represent?

• population proportion

• parameter

• sample proportion

• population sample

A study was done to see if the probability of allergies increased if owning a cat. They randomly sampled 58 people who owned a cat and 34 people who did not own a cat to see if they had allergies or not.

Which hypotheses is correct

A preliminary study suggests that 87% of people agree on an issue. How large must your sample size be so you could be within ± 3% of p calculate at 90% confidence?

• 7

• 466

• 5

• 338