Explain why the given statement is incorrect.

Question

Mark Owens, an optician, estimates that the probability that a customer coming into his store will purchase one or more pairs of glasses but not contact lenses is .35, and the probability that he will purchase one or more pairs of contact lenses but not glasses is .25. Hence, Owens concludes that the probability that a customer coming into his store will purchase neither a pair of glasses nor a pair of contact lenses is .40.

Answer 1

P(G ?C) c ? 1 - P(G) - P(C); he has not considered the case in which a customer buys both glasses and contact lenses.