CMA Foundation · Fundamentals of Business Mathematics and Statistics · Probability
A box at a Pune stationery shop holds 12 blue pens, 8 black pens and 5 red pens. One pen is picked at random. What is the probability that it is not black?
The probability is 17/25. There are 25 pens in all, of which 8 are black, so 17 pens are not black. Probability of not black equals 1 minus 8/25, which is 17/25. The value 8/25 is the chance of black, not of non-black.
- A8/25
- B17/25Correct
- C12/25
- D13/25
Explanation
Total pens = 12 + 8 + 5 = 25. Pens that are not black = 12 + 5 = 17. Probability = 17/25. The option 8/25 is the probability of black, which ignores the word 'not'.
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