Question

. There are two bags A and B. A contains n white and 2 black balls and B contains 2 white and n black balls. One of the two bags is selected at random and two balls are drawn from it without replacement. If both the balls drawn are white and the probability that the bag A was used to draw the balls is 6/7 find the value of n.
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Answer 1

Step-by-step explanation:

For the bag A we can see that there are 2 white, 3 red and 2 black balls. Similarly, from bag B we have 4 white, 2 red and 3 black balls.

Probability of choosing a white and then a red ball from bag B is given by =

9

C

2

4

C

1

×

2

C

1

Probability of choosing a white ball then a red ball from bag A is given by =

7

C

2

2

C

1

×

3

C

1

So, the probability of getting a white ball and then a red ball from bag B is given by

9

C

2

4

C

1

×

2

C

1

+

7

C

2

2

C

1

×

3

C

1

9

C

2

4

C

1

×

2

C

1

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