UPSC CAPF Assistant Commandant Model Paper 6

GIVEN:
3 boys and 4 girls
CONCEPT:
Basic concept of Permutation and combination
Number of ways to select ‘a’ out of ‘b’ =bCa
CALCULATION:
The group should have at least 2 boys.
So, two cases are possible:
2 boys and 2 girls + 3 boys and 1 girl
Required number of ways = 3C2×4C2+3C3×4C1
⇒ 3 × 6 + 1 × 4
⇒ 18 + 4 = 22