SOLUTION: A study of peach trees found that the average number of peaches per tree was 525. The standard deviation of the population is 140 peaches per tree. A scientist wishes to find the

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Question 1035065: A study of peach trees found that the average number of peaches per tree was 525. The standard deviation of the population is 140 peaches per tree. A scientist wishes to find the 80% confidence interval for the mean number of peaches per tree. How many trees does she need to sample to obtain an average accurate to within 14 peaches per tree?
Answer by addingup(3677) About Me  (Show Source):
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Margin of Error (half of confidence interval) 14
The margin of error is defined as the "radius" (or half the width) of a confidence interval for a particular statistic.
Level of Confidence 80
s = Sample standard deviation 140
'z critical value' from Look-up Table for 80% 1.28
significant digits 2
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n = (1.28*140/14)^2
n = Sample Size 163.84 = 164