A marketing research group conducting a telephone survey must contact at least 150 wives and 120 husbands. It costs $3 to make a daytime call and (because of higher labor costs) $4 to make an evening call. On average, daytime calls reach wives 30% of the time, husbands 10% of the time, and neither of them 60% of the time, whereas evening calls reach wives 30% of the time, husbands 30% of the time, and neither of them 40% of the time. Staffing considerations mean that daytime calls must be less than or equal to half of the total calls made. Formulate a linear programming problem that can be used to minimize the cost of completing the survey. Then solve it using any method from this chapter.