Question

The Rover 6 is a new custom-designed sports car. An analysis of the task of building the Rover 6 reveals the following list of relevant activities, their immediate predecessors, and their duration:2 JOB LETTER DESCRIPTION IMMEDIATE PREDECESSOR(S) NORMAL TIME (DAYS) A Start - 0 B Design A 8 C Order special accessories B 0.1 D Build frame B 1 E Build doors B 1 F Attach axles, wheels, gas tank D 1 G Build body shell B 2 H Build transmission and drivetrain B 3 I Fit doors to body shell G,E 1 J Build engine B 4 K Bench-test engine J 2 L Assemble chassis F,H,K 1 M Road-test chassis L 0.5 N Pain body I 2 O Install wiring N 1 P Install interior N 1.5 Q Accept delivery of special accessories C 5 R Mount body and accessories M, O, P,Q 1 S Road test car R 0.5 T Attach exterior trim S 1 U Finish T 0 a) Draw a network diagram for the project. b) Mark the critical path and state its length. c) If the Rover 6 had to be completed 2 days earlier, would it help to: I. Buy preassembled transmissions and drivetrains? II. Install robots to halve engine-building time? III. Speed delivery of special accessories by 3days? d) How might resources be borrowed from activities on the noncritical path to speed activities on the critical path?

Answer 1

a.The network diagram is given below :-

b.The possible paths are :-

A – B – E – I – N- O: 0+8+1.5+1.5+3+2 = 16 days

A-B-E-I-N-P : 0+8+1.5+1.5+3+2.5 = 16.5 days

A-B-G-I-N-O : 0+8+2+1.5+3+2 = 16.5 days

A-B-G-I-N-P : 0+8+ 2+1.5+ 3+2.5 = 17 days

A-B-D-F-L-M: 0+8+ 1.5+1.5+1.5+1 = 13.5 days

A-B-H-L-M :0+8+1+1.5+1 = 11.5 days

A-B-J-K-L-M : 0+8+5+2 +1.5+1 = 17.5 days

A-B-C-Q : 0+8+0.1 + 5 = 13.1 days

The path from R to U is common to all and takes 3 days.

So, the citical path is the path with the maximum time which in this case is :-A-B-J-K-L-M-R-S-T-U

The length of the path is 17.5+3 = 20.5 Days

c. If the Rover 6 had to be completed 2 days earlier, it is would need to be completed in 18.5 days so it would help to

Install robots to halve engine-building time because in that case, it would take 2.5 days instead of the present 5 days and also reduce the order completion time by almost 2 days.

d. The resources on the non-critical path can be borrowed to reduce the time of completion of activities on the critical path and thereby reduce the overall project time.