Confidence Intervals 1

Which of the following is the definition of a "point estimate?"

• The average of a population.

• The average of a sample.

• The midpoint of a confidence interval.

• The confidence interval.

Tags

CCSS.HSS.IC.B.4

The amount added and subtracted to the statistic.

• Margin of Error

• Point Estimator

• Statistic

• Population

Tags

CCSS.HSS.IC.B.4

What is the point estimator for the interval (-5 , 13)?

• 10

• 9.5

• 9

• -5

Tags

CCSS.HSS.IC.B.4

CCSS.HSS.MD.A.2

CCSS.HSS.MD.A.3

What is the margin of error for the interval (6.8, 12.9)?

• 9.85

• 3.05

• 3.50

• 6.8

Tags

CCSS.HSS.IC.B.4

Does the interval (3, 14) support the claim that the mean of a data set is 2.9

• Yes

• No

• Not enough information.

Tags

CCSS.HSS.IC.A.1

Which of the following actions would produce a confidence interval with a smaller width assuming all other contingencies remained constant?

• Using a higher confidence level

• Using a lower confidence level

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.

A researcher studying reaction time of drivers states that, “A 95% confidence interval for the mean time it takes for a driver to apply the brakes after seeing the brake lights on a vehicle in front of him is 1.2 to 1.8 seconds.  What are the point estimate and margin of error for this interval?

• Point estimate = 1.2 seconds; margin of error = 0.6 seconds.
• Point estimate = 1.2 seconds; margin of error = 0.3 seconds.
• Point estimate = 1.5 seconds; margin of error = 0.6 seconds.
• Point estimate = 1.5 seconds; margin of error = 0.3 seconds.

Which of the following sources of error is included in the margin of error

• chance variation in choosing a random sample.
• undercoverage.
• some of the subjects did not understand the questions.
• voluntary response.

Tags

CCSS.HSS.IC.B.4

A 90% confidence interval for the average salary of all CEOs in the electronics industry was constructed using the results of a random survey of 45 CEOs. The interval was ($139,048, $154,144). Give a practical interpretation of the interval.

• 90% of the sampled CEOs have salaries that fell in the interval $139,048 to $154,144
• We are 90% confident that the mean salary of all CEOs in the electronics industry falls in the interval $139,048 to $154,144. 
• 90% of all CEOs in the electronics industry have salaries that fall between $139,048 to $154,144
• We are 90% confident that the mean salary of the sampled CEOs falls in the interval $139,048 to $154,144.