A bag contains 4 white and 5 black balls. A ball is drawn at random from the bag. Find the probability that the ball is drawn is white.

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 ⁿC_r

Now, total no.of ways to pick a ball from 9 balls is ⁹c₁ = 9

Our desired output is to pick a white ball. So, no.of ways to pick a white ball from 4 white balls (because the white ball can be picked from only white balls) is ⁴c₁ = 4

Therefore, the probability of picking a white ball

Conclusion: Probability of picking a white ball from 4 white balls and 5 white balls is