Sections 8.1-8.2 Review

The interval (223.45, 278.05) was found to be a 95% confidence interval for the mean braking distance of 2023 Toyota Tacoma's. Find the margin of error of this interval.

• 54.6

• 27.3

• 250.75

• 1.96

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CCSS.HSS.IC.B.4

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

• Decreasing the sample size

• Increasing the standard deviation

• Decreasing the confidence level

• Increasing the confidence level

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CCSS.HSS.IC.B.4

Which of the following values below represents the critical value z* for a 99.8% confidence interval?

• 3.091

• 0.001

• 2.576

• 0.998

The Graduate Schools of Business and Law and Human sciences want to study the 8,000 recent PhD graduates. The researches take a random sample of 135 recent PhD graduates and found that 9% of PHD graduates are unemployed. Are the 3 conditions met to form a 95% confidence interval?

• No, the random sample condition was not met.

• Yes, all 3 conditions are met.

• No, the 10% condition was not met.

• No because np and n(1-p) are not both greater than 10.

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CCSS.HSS.IC.B.4

The Graduate Schools of Business and Law and Human sciences want to study the 8,000 recent PhD graduates. The researches take a random sample of recent PhD graduates (n = 135) and found that 9% of PHD graduates are unemployed. Which option shows how we would calculate a 95% confidence interval for the proportion of grads who are unemployed?

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• 

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CCSS.HSS.IC.B.4

The Graduate Schools of Business and Law and Human sciences want to study the 8,000 recent PhD graduates. The researches take a random sample of recent PhD graduates (n = 135) and found that 9% of PhD graduates are unemployed. Determine a 95% confidence interval for the proportion of recent PhD graduates who are unemployed.

• (0.042, 0.138)

• (0.049, 0.131)

• (0.027, 0.153)

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CCSS.HSS.IC.B.4

The Graduate Schools of Business and Law and Human sciences want to study the 8,000 recent PhD graduates. The researches take a random sample of recent PhD graduates (n = 135) and found that 9% of PhD graduates are unemployed. The researchers found that a 95% confidence interval for the proportion of unemployed PhD graduates was (0.042, 0.138). Interpret this interval.

• There is a 95% probability that the interval from 0.042 to 0.138 captures the true proportion of all recent PhD graduates who are unemployed.

• If many random samples of recent PhD graduates are taken, about 95% of the created confidence intervals will capture the true population proportion

• We are 95% confident that the interval from 0.042 to 0.138 captures the proportion of recent PhD graduates who are unemployed.

• We are 95% confident that the interval from 0.042 to 0.138 captures the true proportion of all recent PhD graduates who are unemployed.

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CCSS.HSS.IC.B.4

Which choice shows the correct set-up for finding the sample size required to have a margin of error of 0.05 in a 95% confidence interval?

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What is the minimum sample size needed to have a margin of error of 0.05 in a 95% confidence interval?

• 272

• 384

• 385

• 273

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CCSS.HSS.IC.B.4