The confidence interval for a given sample value can be calculated using the following formula:
Confidence interval = Average value ± Margin of error
Which in this case the values are:
Average value = 85%
Margin of error = 12%
Therefore substituting the given values into the equation will give us:
Confidence interval = 85 ± 12
Confidence interval = 73, 97
Therefore the percentage of the residents of the town who are favour of building a new community center ranges from 73% to 97%.
Based from the given choices, only letter B 79% is within this range:
Answer:
B. 79%
