a box contains 24 identical of which 12 are white and 12 are black. the balls are drawn at random from  the box one at time with replacement. the probability that a white ball is drawn for the 4th time on the 7th draw is?

Asked by laks78 | 13th May, 2019, 11:41: PM

Expert Answer:

Let p be the probability of drawing white ball
p = 12/24 = 1/2
Let q be the probability of drawing black ball
q = 12/24 = 1/2
White ball is drawn 4th time in 7th draw i.e. white ball have been drawn thrice in first six draws and 4th time in 7th draw
Required probability = 6C3 (1/2)3 (1/2)3 × (1/2) = 5/32

Answered by Sneha shidid | 14th May, 2019, 09:34: AM

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