Maths · Probability: Probability of an event, addition and multiplication theorems of probability

Assertion If are two events such that =\frac{2}{5}, P(B)=\frac{3}{4} \) then \le

Assertion If \( A \& B \) are two events such that \( P(A)=\frac{2}{5}, P(B)=\frac{3}{4} \) then \( \frac{1}{20} \leq \) \( P(A \cap B) \leq \frac{2}{5} \) Reason \( \boldsymbol{P}(\boldsymbol{A} \cup \boldsymbol{B}) \leq \max \{\boldsymbol{P}(\boldsymbol{A}), \boldsymbol{P}(B)\} \& \) \( \boldsymbol{P}(\boldsymbol{A} \cap \boldsymbol{B}) \geq \min \{\boldsymbol{P}(\boldsymbol{A}), \boldsymbol{P}(\boldsymbol{B})\} \)

  • A. Both Assertion \& Reason are individually true \& Reason is correct explanation of Assertion
  • B. Both Assertion \& Reason are individually true but Reason is not the ,correct (proper) explanation of Assertion
  • C. Assertion is true but Reason is false
  • D. Assertion is false but Reason is true

Step-by-step solution

Assertion: Given P(A)=2/5, P(B)=3/4. For any two events, we have P(A∩B) ≤ min(P(A),P(B))=2/5, and P(A∩B) ≥ max(0, P(A)+P(B)-1)=3/20. Since 1/20 < 3/20, the inequality 1/20 ≤ P(A∩B) holds, so the Assertion is true. Reason: The correct inequalities are P(A∪B) ≥ max(P(A),P(B)) and P(A∩B) ≤ min(P(A),P(B)). The Reason states the opposite, making it false. Hence Assertion true, Reason false.
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