To find the probability of drawing a 4 from Urn A followed by a 2 from Urn B, we will calculate the individual probabilities for each step and then multiply them together, as these events are independent.
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Probability of drawing a 4 from Urn A:
- Urn A has balls numbered from 1 to 7, which means there are 7 possible outcomes.
- There is only 1 ball with the number 4.
- Therefore, the probability of drawing a 4 from Urn A is: \[ P(4 \text{ from A}) = \frac{1}{7} \]
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Probability of drawing a 2 from Urn B:
- Urn B has balls numbered from 1 to 3, which means there are 3 possible outcomes.
- There is only 1 ball with the number 2.
- Therefore, the probability of drawing a 2 from Urn B is: \[ P(2 \text{ from B}) = \frac{1}{3} \]
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Combined probability: Since the events are independent, we multiply the probabilities: \[ P(4 \text{ from A and then } 2 \text{ from B}) = P(4 \text{ from A}) \times P(2 \text{ from B}) = \frac{1}{7} \times \frac{1}{3} = \frac{1}{21} \]
Thus, the probability that a 4 is drawn from A followed by a 2 from B is: \[ \frac{1}{21} \]
Therefore, the answer is:
C. StartFraction 1 Over 21 EndFraction