An animal rescue agent wanted to estimate the true proportion of all animals in shelters that are adopted each month. To do so, she selects a random sample of 100 animals that were in shelters last month and determines that the 95% confidence interval for the true proportion of animals adopted each month is between 0.12 and 0.24. Which of the following would decrease the margin of error?
Answer
A
selecting another sample
B
increasing the sample size
C
decreasing the sample size
D
increasing the confidence level
Explanation
For a proportion, the margin of error gets smaller as the sample size increases, because a larger sample gives a more precise estimate. Therefore, increasing the sample size would decrease the margin of error. Increasing the confidence level would make the interval wider, not narrower.
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