Question

There are 5 black and 4 white balls in a bag. Three balls are drawn one without replacement. Find the probability that the three ball drawn one of the same colour.

Answer 1

Hi there!
Here's the answer:

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No. of Black balls = 5
No. of whiter balls = 4
No. of total balls = 9

Let S be sample space
n(S) - No. of ways of drawing 3 balls from 9
=> n(S) = 9C3 = (9×8×7) /6 = 3×4×7 = 84

E be Event that the 3 balls drawn are of same colour

2 Possibilities:
Either 3 can be Black
or 3 can be White

n(E) = 5C3 + 4C3 = (5×4×3)/6 + (4×3×2)/6
= 10 + 4 = 14

P(E) = n(E)/ n(S) = 14/84 = 1/6

•°• Required Probability = 1/6

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Answer 2

the probability is 1/6...