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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 
64%. The margin of error for the survey was 
3%. Write a confidence interval for the percentage of the population that supports Candidate A.

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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 64% 64 \% . The margin of error for the survey was 3% 3 \% . Write a confidence interval for the percentage of the population that supports Candidate A.

Full solution

Q. 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 64% 64 \% . The margin of error for the survey was 3% 3 \% . Write a confidence interval for the percentage of the population that supports Candidate A.
  1. Understand Confidence Interval: Understand the concept of a confidence interval. A confidence interval gives a range of values within which we can say with a certain level of confidence that the true population parameter lies. In this case, we are looking for the range of percentages within which the true support for Candidate A lies, given a margin of error.
  2. Calculate Lower Bound: Calculate the lower bound of the confidence interval.\newlineTo find the lower bound, subtract the margin of error from the given percentage.\newlineLower bound = 64%3%=61%64\% - 3\% = 61\%
  3. Calculate Upper Bound: Calculate the upper bound of the confidence interval.\newlineTo find the upper bound, add the margin of error to the given percentage.\newlineUpper bound = 64%+3%=67%64\% + 3\% = 67\%
  4. Write Confidence Interval: Write the confidence interval.\newlineThe confidence interval is expressed as (lower bound,upper bound)(\text{lower bound}, \text{upper bound}). Therefore, the confidence interval for the percentage of the population that supports Candidate A is (61%,67%)(61\%, 67\%).

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