हिंदी

Find the probability that in 10 throws of a fair die a score which is a multiple of 3 will be obtained in at least 8 of the throws.

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प्रश्न

Find the probability that in 10 throws of a fair die a score which is a multiple of 3 will be obtained in at least 8 of the throws.

योग
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उत्तर

Here success is a score which is a multiple of 3

i.e., 3 or 6.

Therefore, P(3 or 6) = `2/6 = 1/3`

The probability of r successes in 10 throws is given by

P(r) = `""^10"C"_"r" (1/3)^"r" (2/3)^(10 - "r")`

Now P(At least 8 successes) = P(8) + P(9) + P(10)

= `""^10"C"_8 (1/3)^8 (2/3)^2 + ""^10"C"_9 (1/3)^9 (2/3)^1 + ""^10"C"_10 (1/3)^10`

= `1/3^10 [45 xx 4 + 10 xx 2 + 1]`

= `201/3^10`.

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अध्याय 13: Probability - Solved Examples [पृष्ठ २६५]

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एनसीईआरटी एक्झांप्लर Mathematics Exemplar [English] Class 12
अध्याय 13 Probability
Solved Examples | Q 7 | पृष्ठ २६५

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