In a survey, 30 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $41 and standard deviation of $8. Construct a confidence interval at a 80% confidence level. Give your answers to one decimal place. 40 ± 43 Interpret your confidence interval in the context of this problem.
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The standard error is the standard deviation divided by the square root of the sample size. In this case, the standard deviation is $8 and the sample size is 30. So, the standard error is \( \frac{8}{\sqrt{30}} \approx 1.46 \). Show more…
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