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Mathematics — Standard (041) — CBSE Class 10 board question

Q1. [1] § 14.2 Summary
Assertion (A): If probability of happening of an event is $0.2p$, $p > 0$, then $p$ can't be more than $5$. Reason (R): $P(\bar{E}) = 1 - P(E)$ for an event $E$. Select the correct answer from the options (A), (B), (C) and (D) as given below:
  1. A Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
  2. B Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
  3. C Assertion (A) is true, but Reason (R) is false.
  4. D Assertion (A) is false, but Reason (R) is true.
Previously asked in CBSE board exam
2026 30/4/1 Q19
Generated by claude-sonnet-4-6 · 2026-06-15 10:28 · grounding rag
Model Answer

(A) — Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

Since $P(E) \leq 1$, we need $0.2p \leq 1$, giving $p \leq 5$. This follows directly from the complement rule $P(\bar{E}) = 1 - P(E)$, which ensures $0 \leq P(E) \leq 1$.

Explanation

The assertion is verified: $0.2p \leq 1 \Rightarrow p \leq 5$, so $p$ cannot exceed 5. The reason (complement rule) is the fundamental property that bounds all probabilities between 0 and 1, which is exactly why the assertion holds — making R the correct explanation of A. Choose option (A).

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Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.