CBSE 2024 · Region 5 · Set 3 · Q31 · 3 marks
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 $\displaystyle =0 \times \frac{9}{25}+1 \times \frac{12}{25}+2 \times \frac{4}{25}=\frac{20}{25}=\frac{4}{5}$
| $\displaystyle \mathbf{X}$ | $\displaystyle \mathbf{0}$ | $\displaystyle \mathbf{1}$ | $\displaystyle \mathbf{2}$ |
| $\displaystyle \mathbf{P}(\mathbf{X})$ | $\displaystyle 9 / 25$ | $\displaystyle 12 / 25$ | $\displaystyle 4 / 25$ |
ProbabilityRandom Variable and its Probability DistributionApplyshort_answermedium
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CBSE Class 12 Mathematics past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.