Confidence Interval Review (CPA Stats)

If the 95% Confidence Interval for a population mean is (114.56, 125.54), then is it likely that the true population mean µ is greater than 130?

• Yes

• No

• Not enough information

• I have no idea what you're asking of me

Tags

CCSS.HSS.IC.B.4

True or False:

The more confident you want to be, the smaller your confidence interval will be.

• True

• False

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

True or False:

The larger your confidence interval is, the more sure (higher confidence level) you can be.

• True

• False

Tags

CCSS.HSS.IC.B.4

A sample of 20 cupcakes found the interval for average calories to be (150, 350). Which is the correct interpretation of the 95% confidence interval?

• We are 95% confident that the true mean caloric content can be found with a sample of 150 to 350 cupcakes.

• We are 95% confident that the interval (150, 350) captures the true average caloric content.

• We are 95% confident that a sample of 20 cupcakes will find 250 calories per cupcake.

• None of these are correct.

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.IC.A.1

The football coach randomly selected ten players and timed how long each player took to perform a certain drill. The times (in minutes) were: 13.2, 5.1, 7.5, 8.0, 12.7, 7.6, 13.8, 14.5, 7.7, and 10.5. Determine a 95 percent confidence interval for the mean time for all players.

• 12.30 < μ < 7.82

• 7.82 < μ < 12.30

• 7.70 < μ < 12.42

• 12.15 < μ < 7.97

Tags

CCSS.HSS.IC.B.4

On January 6, just after the National Basketball Association labor dispute was settled, the Gallup Poll asked a random sample of 671 adults: How much have you missed watching NBA basketball since the dispute started?" 60% answered--Not at all." Gallup says that the margin of error for this result is plus or minus 4 percentage points. This means that

• we can be 95% confident that between 56% and 64% of all adults did not miss watching NBA games

• we can be certain that between 56% and 64% of all adults did not miss watching NBA games

• we are 95% confident that if we take one more sample the result will fall between 56% and 64%

• 95% of all the possible samples will fall between 56% and 64%.

Tags

CCSS.HSS.IC.B.4

Which of the following changes to a study would result in a narrower confidence interval?

• increasing the confidence level, increasing the sample size
• decreasing the confidence level, decreasing the sample size
• increasing the confidence level, decreasing the sample size
• decreasing the confidence level, increasing the sample size.

Tags

CCSS.HSS.IC.B.4

In a crash test of 15 troopers, collision repair costs are found to have a distribution that is approximately normal, with a mean of $1800 and a standard deviation of $950. Construct a 95% confidence interval for the repair cost.

• (1309, 2291)

• (1273, 2326)

• (1799, 1801)

• None of these.

Tags

CCSS.HSS.IC.B.4

A 90% confidence interval for a population mean is determined to be 800 to 900. If the confidence is increased to 95% confidence while the sample statistics and sample size remain the same, the confidence interval

• becomes wider
• becomes narrower
• does not change

Tags

CCSS.HSS.IC.B.4

A random sample of 100 visitors to a popular theme park spent an average of $142 on the trip with a standard deviation of $47.5. Which of the following would be the 95% confidence interval for the mean money spent by all visitors to this theme park?

• ($132.55, $151.45)

• ($132.77, $151.43)

• ($132.69, $151.31)

• ($140.88, $143.12)

Tags

CCSS.HSS.IC.B.4