Unit 6 Confidence Interval Proportions test

Given the 95% confidence interval (0.68, 0.79), what is the point estimate?

• 0.68

• 0.055

• 0.028

• 0.79

• 0.735

Given the 95% confidence interval (0.68, 0.79), what is the margin of error?

• 0.68

• 0.055

• 0.028

• 0.79

• 0.735

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CCSS.HSS.IC.B.4

If your confidence level increases from 95% to 99%, what effect will that increase have on the margin of error?

• The margin of error will increase

• The margin of error will decrease

• The margin of error will remain the same

• Not enough information to determine

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CCSS.HSS.IC.B.4

If your sample size decreases from 200 to 50, what effect will that decrease have on your margin of error?

• The margin of error will increase

• The margin of error will decrease

• The margin of error will remain the same

• Not enough information to determine

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CCSS.HSS.IC.B.4

A randomly selected sample of 1,000 college students was asked whether they had ever used a fax machine. Sixteen percent (16% or 0.16) of the 1,000 students surveyed said they had. Which one of the following statements about the number 0.16 is correct? 

 

• It is a randomly chosen number.

• It is a sample proportion. 

• It is a population proportion. 

• It is a margin of error. 

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CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.4

Fatimah wants to estimate the proportion of students who ate breakfast every day last week. She takes a simple random sample of 80 of the 1000 students at her school and finds that 20 of those sampled at breakfast every day last week.

Based on this sample, which of the following is a 95% confidence interval for the proportion of all students at the school who ate breakfast every day last week? 

• 20 ± 0.080

• 20 ± 0.095

• 0.25 ± 0.080 

• 0.25 ± 0.095 

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CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.4

An airline transports over 10,000 passengers daily, and the airline is curious what proportion of their passengers use mobile boarding passes instead of paper passes.  They take a simple random sample of 80 passengers and find that 60 of them use mobile boarding passes.

Based on this sample, which of the following is a 95% confidence interval for the proportion of passengers who use mobile boarding passes?

• (0.625, 0.875)

• (0.637, 0.863)

• (0.655, 0.845)

• (0.670, 0.830)

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CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.4

CCSS.HSS.ID.A.4

A study is used to create a 90% confidence interval for the Presidential approval rating. The resulting interval is (0.48, 0.52). Interpret this interval in context.

• We are 90% confident that the true proportion of people who approve of the President’s job performance is between 0.48 and 0.52.

• 90% of people surveyed will place their proportion of Presidential approval between 0.48 and 0.52.

• If we survey 100 people, 50 of them will say they approve of the President’s job performance.

• A survey of Presidential approval will always be 90% confident of the true proportion.

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CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.4

Maybe do screen shots of the answers and check answer Elena wants to estimate what proportion of computers produced at a factory have a certain defect. A random sample of 200 computers shows that 12 computers have the defect. She is willing to assume independence between computers in the sample.

Based on this sample, which of the following is a 95% confidence interval for the proportion of computers that have the defect?

• 12±1.96 *sqrt ( 12 (200-12)200

• 12±2.57612(200-12)200

• 0.06±1.960.06(1-0.06)200

• 0.062.5760.06(1-0.06)200

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CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.4

CCSS.HSS.ID.A.4