SOLUTION: In a survey, 28 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $48 and standard deviation of $3. Fin

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Question 1079027: In a survey, 28 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $48 and standard deviation of $3. Find the margin of error at a 80% confidence level.
Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
standard error(SE) = 3 / square root(28) = 0.5669
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alpha(a) = 1 - (80/100) = 0.20
p* = 1 - a/2 = 0.90
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critical value(CV) is determined by finding in the z-tables the z-score associated with p*, CV = 1.28
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margin of error(ME) = CV * SE = 1.28 * 0.5669 = 0.7256
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