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Mathematics · 2024 · 3 marks
CBSE 2024 · Region 5 · Set 3 · Q31
An urn contains 3 red and 2 white marbles. Two marbles are drawn one by one with replacement from the urn. Find the probability distribution of the…
An urn contains $\displaystyle 3$ red and $\displaystyle 2$ white marbles. Two marbles are drawn one by one with replacement from the urn. Find the probability distribution of the number of white balls. Also, find the mean of the number of white balls drawn.
Marking-scheme solution
Let $\displaystyle \mathbf{X}=$ Number of white marbles
Mean $\displaystyle =0 \times \frac{9}{25}+1 \times \frac{12}{25}+2 \times \frac{4}{25}=\frac{20}{25}=\frac{4}{5}$
| $\displaystyle \mathbf{X}$ | $\displaystyle \mathbf{0}$ | $\displaystyle \mathbf{1}$ | $\displaystyle \mathbf{2}$ |
| $\displaystyle \mathbf{P}(\mathbf{X})$ | $\displaystyle 9 / 25$ | $\displaystyle 12 / 25$ | $\displaystyle 4 / 25$ |
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CBSE Class 12 Mathematics past-paper question from the 2024 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.