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Probability of solving specific problem independently by A and B are 1/2 and 1/3 respectively. If both try to solve the problem independently, find the probability that - Mathematics

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Question

Probability of solving specific problem independently by A and B are `1/2` and `1/3` respectively. If both try to solve the problem independently, find the probability that

  1. the problem is solved
  2. exactly one of them solves the problem.
Sum

Solution

According to the question, P(A) = `1/2`, P(B) = `1/3`

∴ `"P"(overline"A") = 1 - "P"("A") = 1 - 1/2 = 1/2`

and `"P"(overline"B") = 1 - "P"("B") = 1 - 1/3 = 2/3`

i. ∴ Probability that the problem is not solved by both = `"P"(overlineA ∩ overlineB) = P(overlineA) . P(overlineB)`

= `1/2 xx 2/3`

= `1/3`

∴ The probability that at least one solves the problem

= `1 - P(overlineA ∩ overlineB)`

= `1 - 1/3`

= `2/3` 

ii. The probability that only one person will solve the problem

= P(A ∩ B') + P(A ∩ B')

= P(A) . P(B') + P(A') . P(B)

= `1/2 xx 2/3 + 1/2 xx 1/3`

= `2/6 + 1/6`

= `3/6`

= `1/2`

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Chapter 13: Probability - Exercise 13.2 [Page 547]

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NCERT Mathematics [English] Class 12
Chapter 13 Probability
Exercise 13.2 | Q 14 | Page 547

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