First bag contains 5 white and 4 black balls. Second bag contains 7 white and 9 black balls. A ball is transferred from the first bag to the second bag and then a ball is drawn from the second bag. Find the probability that the ball drawn is white. 

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  1. 7/1
  2. 5/9
  3. 4/9
  4. 11/18

Answer (Detailed Solution Below)

Option 3 : 4/9
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Detailed Solution

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Given:

First bag contains 5 white and 4 black balls.

Second bag contains 7 white and 9 black balls.

Formula Used:

Probability = Number of favorable outcomes / Total number of outcomes

Calculation:

Probability of transferring a white ball from the first bag to the second bag = 5/9

After transferring a white ball, the second bag will have 8 white balls and 9 black balls.

Probability of drawing a white ball from the second bag = 8/17

Probability of transferring a black ball from the first bag to the second bag = 4/9

After transferring a black ball, the second bag will have 7 white balls and 10 black balls.

Probability of drawing a white ball from the second bag = 7/17

Total Probability:

\(\frac{5}{9} \times \frac{8}{17} + \frac{4}{9} \times \frac{7}{17}\)

\(\frac{5}{9} \times \frac{8}{17} + \frac{4}{9} \times \frac{7}{17} = \frac{40}{153} + \frac{28}{153} = \frac{68}{153}\)

⇒ \(\frac{4}{9}\)

The probability that the ball drawn is white is \(\frac{4}{9}\)  .

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