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प्रश्न
A bag contains 5 black balls, 4 white balls and 3 red balls. If a ball is selected randomwise, the probability that it is black or red ball is
पर्याय
1/3
1/4
5/12
2/3
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उत्तर
2/3
Out of 12 balls, one ball can be drawn in 12C1 ways.
∴ Total number of elementary events = 12C1 = 12
Out of fivne black balls, one black ball can be chosen in 5C1 = 5 ways.
Out of three red balls, one red ball can be chosen in 3C1 = 3 ways.
∴ Favourable number of events = 5 + 3 = 8
Hence, required probability = \[\frac{8}{12} = \frac{2}{3}\]
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