Question

There are 3 urns A, B and C each containing a total of 10 marbles of which 2, 7 and 4 respectively are red. One of the urns is selected randomly and a marble is drawn from the selected urn. It is found that the marble is red. What is the probability that the red marble is taken from urn B

Answer 1

The probability that the red marble is taken from urn B is 7/30.

Step-by-step explanation:

To find the probability that the red marble is taken from urn B, we need to consider the probability of selecting urn B and then drawing a red marble from it. Since the urn is selected randomly, each urn has an equal chance of being selected, which is 1/3. The probability of drawing a red marble from urn B is 7/10. Therefore, the probability that the red marble is taken from urn B is the product of these two probabilities:

P(B and red) = P(B) * P(red|B) = (1/3) * (7/10) = 7/30

Answer 2

Answer: 7/13

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Step-by-step explanation:

We know that the marble selected is red, so we don't need to focus on the other colors.

7 red marbles are in urn B out of 2+7+4 = 13 total red marbles.

The probability the red marble came from urn B is therefore 7/13