SOLUTION: A study of peach trees showed that average number of peaches per tree was 1500. The standard deviation is 150. A scientist wishes to find the 90% confidence interval for the mean n

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Question 863091: A study of peach trees showed that average number of peaches per tree was 1500. The standard deviation is 150. A scientist wishes to find the 90% confidence interval for the mean number of peaches per tree. How many trees does she need to sample to be accurate within 14 peaches per tree.
I understand these types of problems, but I dont get how to find the ones without the sample number like this one. could someone please work through this whole problem so I can understand?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A study of peach trees showed that average number of peaches per tree was 1500. The standard deviation is 150. A scientist wishes to find the 90% confidence interval for the mean number of peaches per tree. How many trees does she need to sample to be accurate within 14 peaches per tree.
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Since E = zs/sqrt(n)
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n = [z*s/E]^2
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Your Problem:
n = [1.645*150/14]^2 = 311 when rounded up
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Cheers,
Stan H.
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