EAMCET Engineering 2010 Solved Paper

Case Ist Let a white ball be transfered from the first bag to the second bag.
The probability of selecting white ball from the first bag is P1=‌

3

3+5

=‌

3

8

Now, the second bag has 7 white and 8 black balls. The probability of selecting a white ball from the second bag is P2=‌

7

7+8

=‌

7

15

The probability that both these events take place simultaneously
=P1×P2=‌

3

8

×‌

7

15

=‌

7

40

Case IInd Let a black ball be transfered from the first bag to the second bag.
Its probability is P3=‌

5

3+5

=‌

5

8

Now, the second bag contains 6 white and 9 black balls.
The probability of drawing a white ball from the second bag is P4=‌

6

6+9

=‌

6

15

∴ The probability of both these events taking place simultaneously
=P3×P4=‌

5

8

×‌

6

15

=‌

1

4

∴ The required probability =P1P2+P3P4
‌=‌

7

40

+‌

1

4

‌=‌

7+10

40

=‌

17

40