The weight of potato chips in a large-size bag is stated to be 24 ounces. The amount that the packaging machine puts in these bags is believed to have a normal model with a mean of
24.4 ounces and a standard deviation of 0.22 ounces.
a) What fraction of all bags sold are underweight?
b) Some of the chips are sold in "bargain packs" of 3 bags. What's the probability that none of the 3 is underweight?
c) What's the probability that the mean weight of the 3 bags is below the stated amount?
d) What's the probability that the mean weight of a 20-bag case of potato chips is below
24 ounces?