Question
20 pens are there in a box where 8 are red pens, ‘p’ are blue pens and remaining are black pens. If a pen is picked, the probability of getting blue pen is 0.5. Find the ratio of the number of blue pens and black pens.
Solution
Probability of getting a blue pen , => p/20 = 1/2 => p = 10 So, number of black pens = 20 – 8 – 10 = 2 Required ratio = 10 : 2 = 5:1
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