Suppose the Internal Revenue Service is studying the category of charitable contributions. A sample of 18 returns is selected from young couples between the ages of 20 and 35 who had an adjusted gross income of more than $100,000. Of these 18 returns 4 had charitable contributions of more than $1,000. Suppose 3 of these returns are selected for a comprehensive audit.
What is the probability exactly one of the three audited had a charitable deduction of more than $1,000?
What is the probability at least one of the audited returns had a charitable contribution of more than $1,000?