An urn contains 9 red, 7 white, and 4 black balls. A ball is drawn at

1.	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 or white
Answer» We know that, Probability of occurrence of an event = \(\frac{Total\,no.of\,Desired\,outcomes}{Total\,no.of\,outcomes}\) 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 20 balls is 20_c1 = 20 Our desired output is to pick a white or red ball. So, no. of ways to pick a white or red ball from 16 balls(because there are a total of 16 balls which are either red or white) is ¹⁶c₁ = 16 Therefore, the probability of picking a white or red ball = \(\frac{16}{20}\) = \(\frac{4}{5}\) Conclusion: Probability of picking a white or red ball from 9 red, 7 white, and 4 black balls is \(\frac{4}{5}\)

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 or white

Answer»

We know that,

Probability of occurrence of an event

= \(\frac{Total\,no.of\,Desired\,outcomes}{Total\,no.of\,outcomes}\)

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 20 balls is 20_c1 = 20

Our desired output is to pick a white or red ball. So, no. of ways to pick a white or red ball from 16 balls(because there are a total of 16 balls which are either red or white) is ¹⁶c₁ = 16

Therefore, the probability of picking a white or red ball = \(\frac{16}{20}\) = \(\frac{4}{5}\)

Conclusion: Probability of picking a white or red ball from 9 red, 7 white, and 4 black balls is \(\frac{4}{5}\)

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