1.

A bag contains 6 white and 6 black balls. One by one the balls are drawn from the bag with replacement then the probability that 3rd time a white ball is drawn in 7th draw is:

Answer»

`5/16`
`5/12`
`15/64`
`15/128`

SOLUTION :In first 6 DRAWS 2 white balls are drawn and 7th DRAW to be a white ball.
Required probability `=""^(6)C_(2)(1/2)^(2)(1/2)^(4) xx 1/2 = 15/128`


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