A four-member cultural team is picked at random from the 5 boys and 6 girls of a Class 9 section. What is the probability that the team ends up with at least 3 girls?

Total = $C(11,4)=330$. Exactly 3 girls: $C(6,3)\times C(5,1)=20\times 5=100$. Exactly 4 girls: $C(6,4)=15$. Favourable = 100 + 15 = 115, so the probability is 115/330 = 23/66. Trap 10/33 = 100/330 stops at 'exactly 3 girls' and drops the all-girl team. Trap 1/22 = 15/330 keeps only the all-girl team. Trap 13/66 = 65/330 answers 'at least 3 boys' by reading the two groups the wrong way round.