Question 4 Samples of 20 parts from a metal punching process are selected every hour. Typically 1% of the parts require rework. Let X denotes the number of parts in the sample of 20 that require rework. A process problem is suspected if X exceeds its mean by more than three standard deviations. If the percentage of parts that require rework remains at 1%, what is the probability that X exceeds its mean by more than three standard deviations? b. If the rework percentage increases to 4%, what is the probability that X exceeds 1? a