A marketing research professor is conducting a telephone survey and needs to contact at least 160 wives, 140 husbands, 110 single adult males, and 120 single adult females. It costs $2 to make a daytime call and $4 (because of higher labor costs) to make an evening call. The table shown below lists the expected results. For example, 10% of all daytime calls are answered by a single male, and 15% of all evening calls are answered by a single female. Because of a limited staff, at most half of all phone calls can be evening calls. Determine how to minimize the cost of completing the survey.

PercentagesMorning

Afternoon

Evening

Wife25%

25%

20%

Husband15%

30%

35%

Single male10%

25%

15%

Single female15%

15%

20%

None35%

5%

10%

What are the decision variables in this problem?

a.The number of males and females to call.

b.The number of morning,afternoonand evening calls to make.

c.The number of husbands, wifes, single females and single males to call.

d.The number of calls to make.