Homework Help: statistics

Posted by Jenifer on Monday, October 3, 2011 at 6:12pm.

Assume that a population is normally distributed with a mean of 100 and a standard deviation of 15. Would it be unusual for the mean of a sample of 3 to be 115 or more? Why or why not?

statistics - MathGuru, Tuesday, October 4, 2011 at 5:35pm
Use z-scores:

z = (x - mean)/(sd/√n)
x = 115
mean = 100
sd = 15
n = 3

Once you have z, use a z-table to determine probability. If the probability is low, then it would be unusual for the mean of a sample of 3 to be 115 or more.

I hope this will help.
statistics - Anonymous, Thursday, April 12, 2012 at 5:40pm
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