PERT Sample Questions

Posted on April 28, 2009 by


One of the most common topics read on this blog is the PERT formula. Please see the posting “PMP Exam – PERT Formula” (posted February 6, 2009) for an explanation of this formula. To use this formula, we need three estimates—Optimistic (best-case scenario), Most Likely (realistic), and Pessimistic (worst-case scenario). We then find the average, but we first weight the Most Likely estimate by 4. The formula is (O + (4*ML) + P) / 6. Here are some practice questions:

1. Anne hopes that it takes just 10 hours to make preparations for an important meeting. It will probably take 12 however, and if some key things go wrong, it will take 20 hours. How many hours should be scheduled for the meeting preparations using the PERT formula?
a. 14
b. 15
c. 11
d. 13

2. Tim’s mother-in-law just called. He hopes he can get off the phone in 4 minutes, but he knows she usually talks 20 minutes. If her arthritis is bothering her, the call could be 45 minutes. How many minutes should he plan on being on the phone, using the PERT formula?
a. 21.5
b. 23
c. 21
d. 23.5

3. Ginger is racing her horse against her neighbor’s horse. She hopes her horse will run a fourth of a mile in 30 seconds. Usually her horse runs that distance in 32 seconds, but when he’s grouchy it takes him 37 seconds. How many seconds can she guess her horse will run a fourth of a mile, using the PERT formula?
a. 33
b. 32.5
c. 33.5
d. 35

4. Using the PERT formula, George estimated that a certain report will take 10 days to write. His optimistic guess was 7 days and his pessimistic guess was 13 days. What was his guess for the time it would most likely take to write the report?
a. 10
b. 9
c. 11
d. 20

5. Using the PERT formula, Geraldine estimates that it will take her 6 hours to clean her house. Her optimistic guess was 3 hours and her most likely guess was 5 hours. What was her pessimistic guess?
a. 7
b. 4
c. 12
d. 13

Answers: 1. D; 2. A; 3. B; 4. A; 5. D