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## Probability Concepts

Total 6 balls, 2 Red, 2 Blue and 2 Green.

If the probability of neither draw turning up a blue ball (i.e. no blue balls at all)
4/6 * 3/5 = 12/30 = 2/5 (without replacement)

then , With replacement why the probability of neither draw turning up a blue ball (i.e. no blue balls at all) it is not

4/6 * 4/6 = 16/36 = 4/9 ?

2. Good post? |
Mohican, I am not sure what do you want to know...but in the second case of OA is not giving you the right answer then may be check if the balls are being picked one by one or together...

Else post the original question and let the TMs...solve it for you

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Ok, what I am trying to ask is

There are 6 marbles in a bag. 2 are red, 2 blue and 2 green. Two marbles are drawn randomly with replacement. What the probability that atleast one of them is blue?

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Blue both times: 2/6*2/6
Blue only first : 2/6*4/6
Blue only second : 4/6*2/6

Sum it up: 5/9

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I agree with you, but somebody was saying it to be 8/9.

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Nope : 1 - 4/9 = 5/9.

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No Blue at all = 4/6 * 4/6 = 4/9

At least one blue ball = 1-4/9 = 5/9

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agree with 5/9.

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i wanna know something..

What would the ans be if the question was say,

There are 6 marbles in a bag. 2 are red, 2 blue and 2 green. Two marbles are drawn randomly without replacement. What the probability that atleast one of them is blue?

10. Good post? |
Originally Posted by gre_gal
i wanna know something..

What would the ans be if the question was say,

There are 6 marbles in a bag. 2 are red, 2 blue and 2 green. Two marbles are drawn randomly without replacement. What the probability that atleast one of them is blue?
Probability of no blue= 4/6 * 3/5 = 2/5

Probability of atleast one blue= 1- 2/5 = 3/5