A company has been contracted to do a survey. The firm must assign interviewers to conduct surveys by phone or in person. One person can either conduct 80 phone interviews or 40 in person interviews in a single day. Following is the criteria;
At least 3000 interviews must be conducted
At least 1000 interviews must be done by phone
At least 800 interviews must be personal interview
An interviewer can conduct only one type of interview a day. The cost is $50/day for phone interview and $70/day for personal interview. The firm wants to know the minimum number of interviewers to hire to minimize the total cost of survey.
a. formulate the linear programming model and solve it graphically.
b. determine the sensitivity ranges for the daily cost of a phone interviewer and the number of personal interviewers required.
c. does the firm conduct anymore phone and personal interviews than are required, and if so, how many more?
d. what would be the effect on the optimal solution if the firm was required by the client to increase the number of personal interviews conducted from 800 to 1200?