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101.	A bag contains 6 white and 4 black balls .2 balls are drawn at random. find the probability that they are of same colour.
Answer» let S be the sample space Then n(S)=no of ways of drawing 2 balls out of (6+4)=10c2=(109)/(21)=45 Let E=event of getting both balls of same colour Then n(E)=no of ways(2 balls out of six) or(2 balls out of 4) =(⁶ c₂+⁴ c₂)=(65)/(21)+(43)/(21)=15+6=21 P(E)=n(E)/n(S)=21/45=7/15

101.

A bag contains 6 white and 4 black balls .2 balls are drawn at random. find the probability that they are of same colour.

Answer»

let S be the sample space

Then n(S)=no of ways of drawing 2 balls out of (6+4)=10c2=(10*9)/(2*1)=45

Let E=event of getting both balls of same colour

Then n(E)=no of ways(2 balls out of six) or(2 balls out of 4)

=(⁶ c₂+⁴ c₂)=(6*5)/(2*1)+(4*3)/(2*1)=15+6=21

P(E)=n(E)/n(S)=21/45=7/15

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