Latest self Aptitude Question SOLUTION: A box contains 6 white balls and 7 black balls. Two balls are drawn random. What is the probability that both are the same colour? option A) 5/13 B) 6/13 C) 7/13 D) 6/7

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(#M40030551) SELF question PROBABILITY Keep an EYE

A box contains 6 white balls and 7 black balls. Two balls are drawn random. What is the probability that both are the same colour?
option
A) 5/13
B) 6/13
C) 7/13
D) 6/7

pranshu goyal (10 years ago)

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R.RAVIKUMAR  (10 years ago)

Ans: B
The total no of combinations to get 2 balls= 13c2
The total no of combinations of getting 2 balls of same colour=6c2+7c2
so, the probability is (6c2+7c2)/13c2
i.e. (15+21)/78 = 6/13

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Anchuri Sandeep Reddy  (10 years ago)

There are two ways of of getting both same colour,i.e both white or both black.
So when we get both black, probabilty is (7/13)*(6/12)=42/156.
When we get both white, probavility is (6/13)*(5/12)=30/156.
So total probability of getting both same colour is (42/156)+(30/156)=6/13.

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