The ball team was accused of cheating their soda drinkers by not putting enough soda in their 12 oz. cups. 15 cups were selected at random and found to have a mean of 11.7 oz., sd of 0.5 oz., at a significance level of .01. Test the claim that the customers are being cheated.

Z = (mean1 - mean2)/standard error (SE) of difference between means

SEdiff = √(SEmean1^2 + SEmean2^2)

SEm = SD/√(n-1)

If only one SD is provided, you can use just that to determine SEdiff.

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score.