Answer:
seven
Explanation:
The size of work group is very important since smaller groups tend to be more efficient and finish tasks faster, but they are also less diverse. Ideally if a manager is looking for an efficient group, it should have between 3-5 members. Now if Joe is worried about the lack of diversity, he should consider adding a couple more people, but not that many more. Individual contribution and productivity decreases as the group increases in size.
If you want to enhance creativity and problem solving abilities, you should form diverse groups that include employees with different functional expertise and education.
Out of the possibilities, I would personally choose seven people to form a group in order to keep productivity high and also diversity and creativity.