Answer:
Given
There are 2 rooms
In one room x – 2 boys and 2 girls
That is [B1, B2, G1, G2]
In one room y−1 boy, 3 girls
That is [B3, G3, G4, G5]
∴ When room x is selected, there are four probabilities of members solution
∴ Sample space S = {xB1, xB2, xG1, xG2, yB3, yG3, yG4, yG5}