Probability of Picking a Black Marble from 2nd Urn

In summary: There are three urns with black and white marbles. In each urn, there are 3 black and 3 white marbles. If you pick up a black marble, the probability it was from the second urn is 1/3.
  • #1
sstudent
14
0
1. u have 3 urns and there are black and white marbles in each of them. if u picked a black ball..what is the probabilty it was from the second urn



Homework Equations





3. what i did was that i thought the probailty is 1/3 since there is only 3 marbles..but i aint sure if that's right.
 
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  • #2
Could you quote the question exactly as it is given to you, please. For example, in your attempt at a solution you state that there are only 3 marbles, but this is not given in the question.
 
  • #3
sstudent said:
1. u have 3 urns and there are black and white marbles in each of them. if u picked a black ball..what is the probabilty it was from the second urn



Homework Equations





3. what i did was that i thought the probailty is 1/3 since there is only 3 marbles..but i aint sure if that's right.

You haven't given enough information. HOW MANY black and white marbles are there in each urn? (You say there are 3 urns, not three marbles!) If, for example, there exactly the same number of white and black marbles in each urn, knowing the marble was black wouldn't tell you anything about which urn it came from: probability of each would be, as you say, 1/3. But if one urn have more black marbles than white, while the other two had equal numbers, seeing a black marble would tell you that it was more likely that you picked out of that urn.
 
  • #4
As everyone said, you have given us insufficient information. But when you get them, try what I say. Its just a hint, but if you get it, then its good, else we're always here to give some more hints or help correct your mistakes.

There are three urns and each having black and white marbles. What do you think is the probability of picking up a black marble from second urn, if you had to? Having known that, can you find the reverse, i.e. if you picked a black marble, what is the probability that it came from second urn?

Regards,
Sleek.
 
  • #5
well, it had 10 marbles in the 1st and 2nd urn, and 7 in the 3rd
 
  • #6
But have they not given the individual number of black and white marbles in each of them?

Regards,
Sleek.
 

1. What is the probability of picking a black marble from the 2nd urn?

The probability of picking a black marble from the 2nd urn depends on the total number of marbles in the 2nd urn and the number of black marbles in the 2nd urn. It can be calculated by dividing the number of black marbles in the 2nd urn by the total number of marbles in the 2nd urn.

2. How does the probability change if we pick a black marble from the 1st urn first?

If a black marble is picked from the 1st urn first, the probability of picking a black marble from the 2nd urn changes. This is because the total number of marbles in the 2nd urn decreases by one, and the number of black marbles in the 2nd urn may also decrease if the black marble from the 1st urn is not returned. The new probability can be calculated using the same method as before.

3. Can we use the same formula to calculate the probability if we have more than two urns?

Yes, the same formula can be used to calculate the probability of picking a black marble from the 2nd urn if there are more than two urns. However, the total number of marbles and the number of black marbles in each urn must be taken into account in the calculation.

4. Does the probability change if the marbles in the urns are not evenly distributed?

Yes, the probability of picking a black marble from the 2nd urn can change if the marbles in the urns are not evenly distributed. For example, if there are more black marbles in the 2nd urn compared to the 1st urn, the probability of picking a black marble from the 2nd urn will be higher.

5. Is it possible to calculate the exact probability of picking a black marble from the 2nd urn?

No, it is not always possible to calculate the exact probability of picking a black marble from the 2nd urn. This is because the probability can change depending on various factors such as the order in which the marbles are picked and the distribution of marbles in the urns. However, we can estimate the probability by using mathematical methods and assumptions.

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