Final answer:
The mean duration estimate is the best choice for a project being selected and completed successfully as it considers all values in the data set and represents the central tendency in a normal distribution.
Step-by-step explanation:
If Mei has obtained a graph showing duration data for past projects that follows a normal distribution, the best duration estimate for a project being selected and completed successfully is the mean duration estimate. In a normal distribution, the mean, median, and mode are all the same, or very close to the same value. However, the mean provides the best estimate for the central tendency of normally distributed data because it considers all values in the dataset. This is essential when planning projects, as it accounts for all instances rather than just the most common duration (mode) or the middle value (median), which might not be representative if the data is skewed.
In the context of planning an engineering conference, choosing the mean length as the conference duration could prove advantageous since it reflects the average length of similar events. The mean duration balances out the longer and shorter events, giving attendees and organizers an experience that's tested and familiar. Evidence for this could be seen in the announcements for 84 upcoming engineering conferences where the mean length was 3.94 days, suggesting that a mean duration might be optimal to ensure good attendance and successful completion of the event.