A 99% confidence interval for a population mean is (130, 185). What is the sample mean and the margin of error?

A) Sample mean is 175, margin of error is 140.
B) Sample mean is 140, margin of error is 175.
C) Sample mean is 157.5, margin of error is 17.5.
D) Sample mean is 157.5, margin of error is 27.5.
E) None of the above.

Question

A 99% confidence interval for a population mean is (130, 185).  What is the sample mean and the margin of error?

A)	Sample mean is 175, margin of error is 140.
B)	Sample mean is 140, margin of error is 175.
C)	Sample mean is 157.5, margin of error is 17.5.
D)	Sample mean is 157.5, margin of error is 27.5.
E)	None of the above.

anonymous · Answer

I had E ... but how would you work this out?
I tried to use a zinterval on the TI-84.

ganeshie8 · Answer

sample mean would be same as the population mean

ganeshie8 · Answer

For mean, simply take the mid value of the given confidence interval
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ganeshie8 · Answer

Once you have the mean, you can find the margin of error by finding the distance between mean and either end of the interval

ganeshie8 · Answer

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