ET 1.3.23 (STATS)

Which formula is used to find the Margin of Error for Proportions?

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• 
• Mean ± margin of error

Which formula is used to find the Confidence Interval ?

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• 
• Mean ± margin of error

A survey was given to a random sample of voters in the United States to ask about their preference for a presidential candidate. The percentage of people who said they preferred Candidate A was 33%. The margin of error for the survey was 4.5%. Which of the following is not a reasonable value for the actual percentage of the population that prefers Candidate A?

•  28.1%

• 37.1%

• 35.7%

• 30.3%

A survey was given to a random sample of the residents of a town to determine whether they support a new plan to raise taxes in order to increase education spending. The percentage of people who said the supported the plan to raise taxes was 38%. The margin of error for the survey was 5%. Write a confidence interval for the percentage of the population that favors the plan.

A study by the department of education of a certain state was trying to determine the mean SAT scores of the graduating high school seniors. The study found a confidence interval for the mean score to be between 440 and 472. What is the margin of error on the survey? Do not write ±± on the margin of error.