Question
Question: Three person A<sub>1</sub>, A<sub>2</sub>, A<sub>3</sub> are to speak at a function along with 5 oth...
Three person A1, A2, A3 are to speak at a function along with 5 other persons. If the person speak in random order, the probability that A1 speaks before A2 and A2 speaks before A3 is -
A
1/6
B
3/5
C
3/8
D
None of these
Answer
1/6
Explanation
Solution
Total number of ways in which 8 persons can speak = 8!. Now 3 positions out of 8 positions can be chosen in 8C3 i.e. 56 ways and at these positions we can put A1, A2 and A3 in the required order.
Further the remaining persons can speak in 5! Ways
Ž total number of favourable ways = 56(5!)
Ž required probability = 8!56(5!) = 1/6