SOLUTION: A sample of 36 dieters are in a weight lost program. People who do this program typically loss 40 lbs of weight (with a standard deviation of 12). This sample of dieters lost 45 l

Question 1136580: A sample of 36 dieters are in a weight lost program. People who do this program typically loss 40 lbs of weight (with a standard deviation of 12). This sample of dieters lost 45 lbs. Obtain the z score for this sample.
Answer by Theo(13342) (Show Source): You can put this solution on YOUR website!
population mean is loss of 40 pounds on the average.
population standard deviation is plus or minus 12 pounds on the average.

sample size is 36.

standard deviation of sample means is 12 / sqrt(36) = 12 / 6 = 2

z-score for this sample of 36 dieters is (45 - 40) / 2 = 5/2 = 2.5.

the z-score formula is z = (x-m)/s

z is the z-score
x is the sample mean.
m is the population mean.
s is the standard deviation of the distribution of sample means.

formula for standard deviation of sample means is s = standard deviation of the population divided by the square root of the sample size.

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