ProbabilityHard
Question
Let p be the probability that a man aged x years will die in a year time. The probability that out of ′n′ men A1, A2, A3,......, An each aged ′x′ years. A1 will die & will be the first to die is:
Options
A.
B.p/n
C.
D.
Solution
P = P(1 person lies) + P(2 person lies) P(A 1 lies
first / 2 person lied) + P(3 person lied)
P(A 1 died first / 3 person lied)
= nC1 pqn-1 ×
+ nC1 p2 qn-2 ×
+ nC2 p3qn-3 ×
+ ....
= pqn-1 + n-1Cr-1 p2qn-2
+ nC3 p3qn-3
+ .....
= pqn-1 +
P = Pqn-1 +
⇒ P = pqn - 1 +
(1 - nC0 p0 qn - nC1 P1 qn-1)
P = Pqn-1 +
(1 - qn - nPqn-1) = 
first / 2 person lied) + P(3 person lied)
P(A 1 died first / 3 person lied)
= nC1 pqn-1 ×
= pqn-1 + n-1Cr-1 p2qn-2
= pqn-1 +
P = Pqn-1 +
⇒ P = pqn - 1 +
P = Pqn-1 +
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