1.[36/(1+3+8)] * (1+3+8+7+2) = 63 (person)

2. The third group: 7/(63 * 8/21) = 7/24;

Group 5: 2/(63*2/2 1)= 1/3,

And 24 July.

So the fifth group is higher.

(2)

Compare a and b first, as follows:

When a>b, if a>c, then A is the largest;

If a<c, then c is the largest.

When a<b, if b>c, then B is the largest;

If b < C, then c is the largest.