Question 15 - CBSE Class 12 Sample Paper for 2021 Boards - Solutions of Sample Papers and Past Year Papers - for Class 12 Boards
Last updated at August 14, 2026 by Teachoo
The probabilities of A and B solving a problem independently are 1/3 𝑎𝑛𝑑 1/4 respectively. If both of them try to solve the problem independently, what is the probability that the problem is solved?
Note
: This
is similar
to
Ex 13.2, 14
of NCERT –
Chapter 13 Class 12 Probability
Question 15 The probabilities of A and B solving a problem independently are 1/3 𝑎𝑛𝑑 1/4 respectively. If both of them try to solve the problem independently, what is the probability that the problem is solved?
Given,
P(A) = 1/3 & P(B) = 1/4
Probability that the problem is solved
= Probability that A solves the problem or B solves the problem
= P(A ∪ B)
= P(A) + P(B) – P(A ∩ B)
Since A & B are independent,
P(A ∩ B) = P(A) . P(B)
= 1/3 × 1/4 = 1/12
Now,
P(Problem is solved) = P(A) + P(B) – P(A ∩ B)
= 1/3 + 1/4 – 1/12
= 4/12 + 3/12 – 1/12
= 6/12
= 𝟏/𝟐
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