The only types of groups of 5 are these:
1. 4 girls, 1 boy C(4,4)C(7,1) = (1)(7) = 7 ways
2. 3 girls, 2 boys C(4,3)C(7,2) = (4)(21) = 84 ways
3. 2 girls, 3 boys C(4,2)C(7,3) = (6)(35) = 210 ways
4. 1 girl, 4 boys C(4,1)C(7,4) = (4)(35) = 140 ways
5. 0 girls, 5 boys C(4,0)C(7,5) = (1)(21) = 21 ways
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Total = 462 ways
1. no girl ==> case 5 DISABLED_event_only= => 21 ways
2. at least one boy and one girl ==> all cases except case 5 ==> 462-21 = 441 ways
3. at least 3 girls ==> cases 1 and 2 DISABLED_event_only= => 7+84 = 91 ways
Edwin