Suppose that the four inspectors at a film factory are supposed to stamp the expiration date on each

package of film at the end of the assembly line. John who stamps 20% of the packages, fails to stamp the

expiration date once in every 200 packages; Tom, who stamps 60% of the packages, fails to stamp the

expiration date once in every 100 packages; Jeff, who stamps15% of the packages, fails to stamp the

expiration date once in every 90 packages; and Pat, who stamps 5% of the packages, fails to stamp the

expiration date once in every 200 packages. If a customer complains that her package of film does not

show the expiration date, what is the probability that it was inspected by John?