ProbabilityHard
Question
7 persons are stopped on the road at random and asked about their birthdays. If the probability that 3 of them are born on Wednesday, 2 on Thursday and the remaining 2 on Sunday is 
, then K is equal to -
, then K is equal to -Options
A.15
B.30
C.105
D.210
Solution
Probability that 3 people out of 7 born on
Wednesday =
Probability that 2 people out of remaining 4, born on Thursday is
Probability of remaining 2 born on Sunday is
∴ required probability =
⇒ K = 30
Wednesday =
Probability that 2 people out of remaining 4, born on Thursday is
Probability of remaining 2 born on Sunday is
∴ required probability =
⇒ K = 30
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