An urn contains 9 red, 7 white, and 4 black balls. A ball is drawn at random. Find the probability that the ball is drawn is

red


We know that,


Probability of occurrence of an event


By permutation and combination, total no.of ways to pick r objects from given n objects is nCr


Now, total no.of ways to pick a ball from 20 balls is 20c1 = 20


Our desired output is to pick a red ball. So, no.of ways to pick a red ball from 9 red balls (because the red ball can be picked from only red balls) is 9c1 = 9


Therefore, the probability of picking a red ball


Conclusion: Probability of picking a red ball from 9 red,


7 white and 4 black balls is


1