DNA_REPAIRS is a chain of computer service stores. The number of hours of skilled repair time that it reauires during the next six months is as follows: At the beginning of January, 47 skilled technicians work for DNA_REPAIRS. Each skilled technician can work up to 150 hours per month. To meet future demands, new technicians must be trained. It takes one month to train a new technician. During the month of training, a trainee must be supervised for 55 hours by an experienced technician. Each experienced technician is paid $3,500 a month (even if he or she does not work the full 150 hours). During the month of training, a trainee is paid $1,800a month. At the end of each month, approximately 7.5\% of DNA_REPAIRS's experienced technicians quit to join a competitor. Formulate an LP whose solution will enable DNA_REPAIRS to minimize the labor cost incurred in meeting the service requirements for the next six months. a) Formulate the corresponding LP model and solve it using Excel assuming that all variables are continuous. Explain the optimal solution. b) Solve the problem using Excel assuming that the number of workers hired each month have to be integer. Clearly explain the optimal solution