6.1 Two for the money

The times required to complete each of seven jobs in a two-machine flow shop are shown in the table below. Each job must follow the same sequence, beginning with machine X and moving to machine Y.

A. Determine a sequence that will minimize makespan time

B. Construct a chart of resulting sequence, and find machine Ys idle time

C. For the sequence determined in part (a), how much would machine Ys idle time be reduced be splitting the last two jobs in half?

("halving" means dividing the work into two equal parts (e.g. 4+8 -> 2+4 & 2+4))

6.2 Big Four

An accounting firm forecasts the following workload during the tax season: Personal tax returns each require 1,5 hours of an accountants time, and corporate returns each require 4 hours. During tax season, each accountant can work up to 10 hours per day. However, error rates increase to unacceptable levels when accountants work more than five consecutive days per week.

A. Create an effective and efficient work schedule

B. Assume that Big Four has three part-time employees available to work three days per week (does not have to be consecutive). How could these employees be effectively utilized?

(the number of employees must be rounded up (i.e. seven employees are needed to make 61 working hours))

\begin{tabular}{|c|c|c|} \hline Job & Machine X & Machine Y \\ \hline a & 6 & 4 \\ \hline b & 8 & 2 \\ \hline c & 3 & 4 \\ \hline d & 10 & 7 \\ \hline e & 6 & 5 \\ \hline f & 9 & 6 \\ \hline g & 4 & 10 \\ \hline \end{tabular} \begin{tabular}{|c|c|c|c|c|c|c|c|} \hline Job & Mon & Tue & Wed & Thu & Fri & Sat & Sun \\ \hline Personaltaxreturns & 24 & 14 & 18 & 18 & 10 & 28 & 16 \\ \hline Corporatetaxreturns & 18 & 10 & 12 & 15 & 24 & 12 & 4 \\ \hline \end{tabular}