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MHT CET · Maths · Probability

Let A and B be two events such that the probability that exactly one of them occurs is \(\frac{2}{5}\) and the probability that A or B occurs is \(\frac{1}{2}\), then the probability of both of them occur together is

  1. A 0.1
  2. B 0.2
  3. C 0.01
  4. D 0.02
Verified Solution

Answer & Solution

Correct Answer

(A) 0.1

Step-by-step Solution

Detailed explanation

Given that,
\(\mathrm{P}\left[\left(\mathrm{~A} \cap \mathrm{~B}^{\prime}\right) \cup\left(\mathrm{A}^{\prime} \cap \mathrm{B}\right)\right]=\frac{2}{5}...(i)\)
and \(P(A \cup B)=\frac{1}{2}\)...(ii)
From (i), we get
\(\mathrm{P}(\mathrm{~A})+\mathrm{P}(\mathrm{~B})-2 \mathrm{P}(\mathrm{~A} \cap \mathrm{~B})=\frac{2}{5}...[From(i)]\)
\(\begin{array}{ll}\therefore & P(A \cup B)-P(A \cap B)=\frac{2}{5} \\ \therefore & \frac{1}{2}-P(A \cap B)=\frac{2}{5} \\ \therefore & P(A \cap B)=\frac{1}{2}-\frac{2}{5}=\frac{1}{10}=0.1\end{array}\)