I would like to create a macro that gives the different results for the
following

Question:
I have 20 numbers (1-20) that are broken down into three groups. How can I
create a macro that generates different sets of 3 groups of numbers, that
when any 5 numbers are picked at random, at least four (80%) of the five
numbers will be in a group? Each number is used once per set. The objective
is to generate the least amount of sets to accomplish this goal.

Partial Answer:
Set 1
Group 1 = 1, 2, 3, 4, 5, 6, 7
Group 2 = 8, 9, 10, 11, 12, 13, 14
Group 3 = 15, 16, 17, 18, 19, 20

Set 2
Group 1 = 20, 14, 6, 18, 10, 12, 4
Group 2 = 16, 8, 2, 3, 7, 11, 15
Group 3 = 1, 5, 9, 11, 17, 19

Set 3
Group 1 = 3, 6, 9, 12, 15, 18 1
Group 2 = 4, 7, 10, 13, 16, 19, 5
Group 3 = 2, 8, 11, 14, 17, 20

And so on€¦€¦€¦€¦.

In other words,

Question:
I have 20 employees that on average 5 of them will complain about different
working conditions (or other problems) per month. Each employee will be
listed/named 1-20 in excel. The 20 employees are broken down into 3 groups.
How many different sets of 3 groups (numbered 1-20 where each number can only
be used once per set) will I have to create to have at least 4 out of 5
random complaints end up in the same group? The objective is to accomplish
this goal by using the least amount of sets.

Can I create a macro for this? I'm using Microsoft Excel 2002. Thanks