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Question
Find the probability of getting both red balls, when from a bag containing 5 red and 4 black balls, two balls are drawn, without replacement
Solution
There are 9 balls i.e. 5 red and 4 black.
When balls are drawn without replacement, first ball can be drawn in 9 ways.
After that second ball can be drawn in 8
∴ n(S) = 9 × 8 = 72
First red ball can be drawn in 5 ways
∵ ball is not replaced, second red ball can be drawn in 4 ways
∴ two red balls can be drawn in 5 × 4 = 20 ways
∴ the required probability = `20/72` = `5/18`
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