Reconsider the Electronic Toys Co. problem presented in Prob. 22.4-5. Sharon Lowe is concerned that there is a significant chance that the vitally important deadline of 57 days will not be met. Therefore, to make it virtually certain that the deadline will be met, she has decided to crash the project, using the CPM method of time-cost tradeoffs to determine how to do this in the most economical way.
Sharon now has gathered the data needed to apply this method, as given below.

The normal times are the estimates of the means obtained from the original data in Prob. 22.4-5. The mean critical path gives an estimate that the project will finish in 51 days. However, Sharon knows from the earlier analysis that some of the pessimistic estimates are far larger than the means, so the project duration might be considerably longer than 51 days. Therefore, to better ensure that the project will finish within 57 days, she has decided to require that the estimated project duration based on means (as used throughout the CPM analysis) must not exceed 47 days.
(a) Consider the lower path through the project network. Use marginal cost analysis to determine the most economical way of reducing the length of this path to 47 days.
(b) Repeat part (a) for the upper path through the project network. What is the total crashing cost for the optimal way of decreasing estimated project duration of 47 days?
(c) Use Excel to solve the problem.

Crash Normal Time Crash Cost Normal Activity Cost Time 12 days9 days $210,000 $270,000 15 days 12 days 18 days14 days 23 days18 days 410,000 290,000 350,000 160,0002 460,000 320,000 500,000 410,000 210,000 27 days 21 days440, 6 days 4 days