Engineering
Mathematics
Conditional Probability
Question

Three boys and two girls stand in a queue. The probability, that the number of boys ahead of every girl is at least one more than the number of girls ahead of her, is

 12

 13

 34

 23

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Solution

possible cases

Case‑I: B G G B B

Case‑II: G G B B B

Case‑III: G B G B B

Case‑IV: B G B G B

Case‑V: G B B G B

Number of boys ahead of every girl is at least one more than the number of girls ahead of her, is 5×3!×2!5!=5×6×2120=12