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Question
A jar contains 24 marbles. Some of these are green and others are blue. If a marble is drawn at random from the jar, the probability that it is green is `2/3`. Find the number of blue marbles in the jar.
Solution
Total number of marbles = 24.
Let the number of blue marbles be x.
Then, the number of green marbles = 24 − x
∴ P(getting a green marble) = `("Number of favourable outcomes")/"Number of all possible outcomes"`
`= (24-x)/24`
But, P (getting a green marble) = 2/3 (given)
`therefore (24-x)/24 = 2/3`
⇒ 3 (24 - x) = 48
⇒ 72 - 3x= 48
⇒ 3x = 24
⇒ x = 8
Thus, the number of blue marbles in the jar is 8.
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