You are trying to plan out when you need to leave in the morning. When you first wake up, you take your time getting out of bed (A). You then decide to walk to the coffee maker and begin brewing some coffee (B). As the coffee brews (C), you then take your dog outside (D) and bring him back inside where you give him his first meal (E). You then sit down for your cup of coffee (F). After drinking your cup of coffee, you proceed to get dressed and pack your bag for the day (G). While all of this is going on, your roommate has been getting ready (H); you two carpool together to your university; therefore, you need to both be prepared in order to leave (you can assume you two wake up at the same time). You two then ride together to NCSU where you begin your day (I). Operation with label Optimistic time Most Likely time Pessimistic time
estimate (minutes) estimate (minutes) estimate (minutes)
Get out of bed (A) 1 3 10
Walk to/Start coffee maker (B) 2 3 5
Coffee brews (C) 7 8 9
Take your dog outside (D) 3 5 10
Feed your dog (E) 1 2 3
Drink your cup of coffee (F) 6 9 12
Dress/Pack for the day (G) 8 10 13
Roommate gets ready (H) 25 28 42
Ride to NCSU (I) 10 15 21
a. Assuming that this is a deterministic PERT chart (using the "most likely time estimates" as the normal activity times), develop the PERT Chart.
b. Identify the critical path.
c. Assuming this is a deterministic system, how long will it take to arrive on campus?
d. A review of your routine reveals that representing it deterministically is a gross oversimplification, so you decide to use the PERT 3 estimate technique to evaluate the system probabilistically. In other words, calculate the expected time and variance for arriving at NC State. Note: Round to the nearest integers for expected times and variances.
e. Your friend asks for the probability that you will be on campus within 46min. What is your reply?
f. Another friend wants to meet with you at 10 am. When should you get up to be 95% sure that you will be on campus by 10 am?