statistics
posted by Mk .
Five percent of all items sold by a mailorder company are returned by customers for a refund. Find the probability that of two items sold during a given hour by this company both will be returned for a refund (round to four decimal places).

It's just 0.05 x 0.05 = 0.0025. The fact that they were both sold during a given hour is irrelevant to the calculation, BUT you're assuming when you perform that calculation that the returning of one item is independent of whether or not another one is returned. Given that they were both sold within such a small interval of time, you might feel the need to question that assumption.