Consider a class of 5 girls and 7 boys. The number of different teams consisting of 2 girls and 3 boys that can be formed from this class, if there are two specific boys A and B, who refuse to be the members of the same team, is:
- (A)500
- (B)200
- (C)300✓ Correct
- (D)350
Answer: (C)
Solution
Count all valid teams, then strike out the forbidden ones. Choosing girls from and boys from gives teams. The teams putting both A and B together use those two boys plus one of the remaining five and any two girls: . Subtracting, teams keep A and B apart.
JEE Main · 2019 · 09 Jan 2019 · Shift 1 · Single correct option