PS_9.11.1 Video Lesson - Confidence Intervals and Sample Means

What is a confidence interval?

• A single value representing the true mean of a population

• A range of values that surrounds the mean of a sample, providing a level of confidence about the true population mean

• The exact mean of a population

• A measure of the variability within a sample

How does increasing the sample size (n) affect the width of the confidence interval?

• It makes the confidence interval wider

• It makes the confidence interval narrower

• It has no effect on the width of the confidence interval

• It only affects the z-score, not the width

How does increasing the standard deviation affect the confidence interval?

• Increasing the standard deviation increases the width of the confidence interval.
• Increasing the standard deviation decreases the width of the confidence interval.
• Increasing the standard deviation has no effect on the confidence interval.
• Increasing the standard deviation narrows the confidence interval.

What is the new confidence interval for a confidence level of 75%?

• (172.1, 179.9)

• (173.7, 178.3)

• (175.9, 176.1)

• (173.3, 178.7)

What is the new confidence interval if the sample size is increased to 500?

• (172.1, 179.9)

• (173.7, 178.3)

• (175.3, 176.7)

• (174.8, 177.2)