posted by Jerry .
a machine fills containers with a standard deviation of filling weights of 1.5. calculate the mean weight if only 4 % of the containers hold less than 19 ounces
Z = (score-mean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion and its Z score. Insert the Z score and the other values in the above equation and solve for the mean.