Confidence Intervals

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

Given: p = 0.30, n = 36. Calculate: 90% confidence interval

• (0.175, 0.425)

• (0.155, 0.456)

• (0.108, 0.503)

• (0.202, 0.398)

Tags

CCSS.HSS.IC.B.4

Given: p = 0.08, n = 100. Calculate: 99% confidence interval

• (0.027, 0.133)

• (0.0354, 0.125)

• (0.010, 0.150)

• (0.041, 0.119)

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CCSS.HSS.IC.B.4

A study found that in a sample of 44 subjects, 9 of agree that children under 6 shouldn’t be taken to nice restaurants. Calculate a 95% confidence interval for p.

• (0.105, 0.305)

• (0.082, 0.318)

• (0.117, 0.292)

• (0.048, 0.361)

Tags

CCSS.HSS.IC.B.4

A survey of 121 subjects found that 84 have suffered the symptoms of depression in the last year.

A 90% confidence interval for p is (0.621, 0.759). Interpret this interval.

• Based on this sample, I am 90% confident that the true proportion of people who have suffered the symptoms of depression in the last year is between 62.1% and 75.9%.

• 90% of the time, the population of people who have suffered the symptoms of depression in the last year is between 62.1% and 75.9%

• 90% of all of the possible intervals calculated using this method will capture the true proportion of people who have suffered the symptoms of depression in the last year.

• The probability that people who have suffered the symptoms of depression in the last year is between 62.1% and 75.9% is 90%.

Tags

CCSS.HSS.IC.B.4

The symbol for the sample proportion is __________.

• Z_c
• p̂
• E
• q

Tags

CCSS.HSS.IC.B.4

A survey of 80 recent fatal traffic accidents showed that 46 were alcohol-related. Find the 98% CI.

• (-30.01, 122.01)
• (45.87, 46.13)
• (.45, .70)
• (.29, .55)

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.

The amount added and subtracted to the statistic.

• Margin of Error

• Point Estimator

• Statistic

• Population

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.