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Mathematics · 2024 · 3 marks
CBSE 2024 · Region 5 · Set 2 · Q31
A jar contains $\displaystyle 54$ marbles, each of which is blue, green or white. The probability of selecting a blue marble at random from the jar is $\displaystyle \frac{1}{3}$, and the probability of selecting a green marble at random is $\displaystyle \frac{4}{9}$. How many white marbles does this jar contain ?
Marking-scheme solution
Let number of white marbles in the jar \(\displaystyle =x\)
\[\begin{aligned}
\therefore & \mathrm{P} \text { (white marbles) }=\frac{x}{54} \\
& \frac{x}{54}=1-\frac{1}{3}-\frac{4}{9} \\
& \mathrm{x}=12
\end{aligned}
\]
Hence, the number of white marbles = $\displaystyle 12$
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CBSE Class 10 Mathematics past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.