There are 15 jobs that must be done by 10 employees. Each job must be done by a single employee, and each employee can do at most two jobs. The time (in minutes) for the employees to do the jobs are listed in the file P05_70.xlsx, where blanks indicate disallowed assignments.

a. assuming that not all employees have to be assigned, find the assignments that minimize the total time to complete all jobs. For each of the 15 jobs, enter the corresponding employee number from 1 to 10.

b. how much longer does it take to complete all jobs if every employee must be assigned to at least one job?