AP Stats

Identify the confidence interval used in the figure below if each shaded area is equal to 0.05.

• 90%

• 95%

• 98%

• 99%

To find a z-score, use InvNorm(1-c).

• True
• False

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

Find the value of z* for a 93% confidence interval.

• -1.96

• 1.645

• 1.881

• -1.598

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

1) A 90% confidence interval for the mean speed driven by cars on Skillman road is given by (21, 45). What was the sample mean of this study?

A 90% confidence interval for the mean speed driven by cars on Skillman road is given by (21, 45). What was the margin of error of this study?

The confidence interval obtained will always correctly find the exact true population parameter.

• True

• False

Exact confidence intervals for a small sample size can be calculated even without knowing the critical values.

• True

• False

The confidence level tells us the chance that a particular confidence interval captures the population parameter.

• True

• False