The following Guest article is an extract from the book Project Decisions: The Art and Science By authors Lev Virine and Michael Trumper, published by Management Concepts, Inc.© 2008. Reproduced with permission. Published here July 2008.

## Questions 1 to 4

1.   You are a project manager working on a movie called Pirates of the Caribbean-24. Your project is to produce and deliver a prop for the set: a treasure chest. You estimate that manufacturing the chest in China and filling it with gold will take between 10 days (you have 10% confidence in this estimate) and 40 days (90% confidence) using normal distribution. Delivery time should be the same in all cases. The director has requested that you come up with an estimate with 90% confidence for both manufacturing and shipping the treasure chest. Which of the following is your estimate?

 A. ~80 days B. ~50 days C. ~63 days.

2.   You are an artist drawing a wedding portrait of Katie Holmes and Tom Cruise. You have two strategies: (1) Draw both of them at the same time. This strategy will take 20 days. However, if at any time during the 20 days, Katie and Tom decide that they do not like the portrait, you have to start all over. The probability of them not liking your work is 60%. (2) Draw Katie first and then Tom. This strategy will take 10 days for each of them. If at any time during these 10 days Katie or Tom decides that they do not like their portraits, you will need to restart your 10 days of work. The probability of either of them not liking your work is 30%. Which strategy should you use to complete the portrait faster (on average, taking into account potential delays)?

 A. Both strategies will lead to the same duration. B. Strategy B is 17% faster than strategy A. C. Strategy B is 70% faster than strategy A.

3.   Assume that you selected strategy 2 from the previous question. There could be two scenarios: (a) Katie's and Tom's art preferences are similar, so if Katie doesn't like the portrait, Tom probably won't like it either; or (b) Katie's and Tom's preferences are different. What is the project duration (on average, taking into account potential delays)?

 A. Situation A leads to a 50% faster completion of the portrait than situation B. B. Situation B leads to a 50% faster completion than situation A. C. Portrait completion times in situation A and B are about the same.

4.   You are the organizer of a Rolling Stones concert in your town, and you need to replace many amplifiers in the stadium where the concert will take place. You know, based on independent testing, that only 1% of all the amplifiers are defective, but you decide to test them anyway. The test is 80% accurate; therefore, in 20% of the cases the amplifiers could pass the test but stop working during the concerts. Your test indicates that a particular amplifier is defective. What is the probability that the other amplifiers will be defective?

 A. 80% B. 40% C. 4%