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Mathematics — CBSE Class 10 board question

Q1. [1]
In a group of 20 people, 5 can't swim. If one person is selected at random, then the probability that he/she can swim, is
  1. A $\dfrac{3}{4}$
  2. B $\dfrac{1}{3}$
  3. C 1
  4. D $\dfrac{1}{4}$
Previously asked in CBSE board exam
2023 30/1/1 Q18
Generated by claude-sonnet-4-6 · 2026-06-15 10:31 · grounding rag
Model Answer

Total people = 20; people who can swim = 20 − 5 = 15.

$$P(\text{can swim}) = \frac{15}{20} = \frac{3}{4}$$

Answer: A $\dfrac{3}{4}$

Source: Chapter 14, Section 14.1

Explanation

Subtract the 5 non-swimmers from 20 to get 15 favourable outcomes, then apply the formula P(E) = favourable outcomes ÷ total outcomes. Examiner expects the subtraction step shown and the fraction simplified to 3/4.

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