A graphite manufacturer makes long
rolls of flexible graphite to be used to seal components in
combustion engines. The specifications state that the mean
strength should be 21.2 ounces per square yard with a
standard deviation of 0.29. Further specifications state that
no roll should have strength less than 20.2 or more than
22.2 ounces per square yard. If there is a defect in terms
of the strength of the graphite rolls, the seal will not hold.
After the roll is created, a beta scanner takes readings of
the basis weight in ounces per square yard. The data is
separated into 10 lanes with 20 scans in each lane. A sample
consists of one roll from each lane. The results from 20
samples follow are in the data.