The probability that a child will have a problem with alcohol is .75 if at least one of the parents is an alcoholic and .05 if neither parent is an alcoholic. In a recent study of a large number of children, 5% of the children involved had at least one parent who is an alcoholic. If a child in this study has an alcohol-related problem, what is the probability that at least one of the parents of the child is an alcoholic?