Class CBSE Class 12 Mathematics Probability Q #1471
COMPETENCY BASED
UNDERSTAND
2 Marks 2025 AISSCE(Board Exam) VSA
In a village of 8000 people, 3000 go out of the village to work and 4000 are women. It is noted that 30% of women go out of the village to work. What is the probability that a randomly chosen individual is either a woman or a person working outside the village?

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Detailed Solution

Step 1: Define Events

Let $W$ be the event that a randomly chosen individual is a woman. Let $O$ be the event that a randomly chosen individual works outside the village.

Step 2: Calculate Probabilities

We are given the following information: Total number of people in the village = 8000 Number of people who go out of the village to work = 3000 Number of women = 4000 Percentage of women who go out of the village to work = 30%

Step 3: Calculate P(W)

The probability that a randomly chosen individual is a woman is: $$P(W) = \frac{\text{Number of women}}{\text{Total number of people}} = \frac{4000}{8000} = \frac{1}{2}$$

Step 4: Calculate P(O)

The probability that a randomly chosen individual works outside the village is: $$P(O) = \frac{\text{Number of people working outside}}{\text{Total number of people}} = \frac{3000}{8000} = \frac{3}{8}$$

Step 5: Calculate P(W ∩ O)

We are given that 30% of women go out of the village to work. So, the number of women who work outside the village is: $$0.30 \times 4000 = 1200$$ The probability that a randomly chosen individual is a woman and works outside the village is: $$P(W \cap O) = \frac{\text{Number of women working outside}}{\text{Total number of people}} = \frac{1200}{8000} = \frac{3}{20}$$

Step 6: Calculate P(W ∪ O)

We want to find the probability that a randomly chosen individual is either a woman or a person working outside the village, which is $P(W \cup O)$. Using the formula for the union of two events: $$P(W \cup O) = P(W) + P(O) - P(W \cap O)$$ $$P(W \cup O) = \frac{1}{2} + \frac{3}{8} - \frac{3}{20} = \frac{20}{40} + \frac{15}{40} - \frac{6}{40} = \frac{20 + 15 - 6}{40} = \frac{29}{40}$$

Final Answer: 29/40

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Pedagogical Audit
Bloom's Analysis: This is an UNDERSTAND question because the student needs to understand the concepts of probability, union of events, and intersection of events to solve the problem. They must also be able to apply the formula for the union of two events.
Knowledge Dimension: CONCEPTUAL
Justification: The question requires understanding of probability concepts like union and intersection of events, rather than just recalling facts or performing calculations.
Syllabus Audit: In the context of CBSE Class 12, this is classified as COMPETENCY. The question requires the application of probability concepts to a real-world scenario, testing the student's ability to apply their knowledge.

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