Question 4 Before a new product can be introduced, the activities in the table following must be completed. Times are in weeks. Activity Description Predecessors a m b A Design the product N B Survey the market C Place orders for raw materials A D Receive raw materials C NAAWNWUD E Build prototype of product A, D ONWHEN. F Develop ad campaign B G Set up plant for mass production E H Deliver products to stores G. F (a) Draw the project network diagram. (b) Calculate the expected duration and variance of all activities. (c) Determine ES, LS, EF and LF for each activity. (d) Calculate the slacks and determine all critical paths and critical activities. (e) Assume it is now 19 weeks before Christmas Day. What is the probability that the product will be in stores before then? (f) What time should we allow, if we want a 99% chance that the product will be ready