मराठी

Three numbers are chosen from 1 to 20. Find the probability that they are not consecutive ______.

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प्रश्न

Three numbers are chosen from 1 to 20. Find the probability that they are not consecutive ______.

पर्याय

  • `186/190`

  • `187/190`

  • `188/190`

  • `18/(""^20C_3)`

MCQ
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उत्तर

Three numbers are chosen from 1 to 20. Find the probability that they are not consecutive `187/190`.

Explanation:

Set of three consecutive numbers from 1 to 20 are 1, 2, 3; 2, 3, 4; 3, 4, 5; ..., 18, 19, 20.

So, the probability that the numbers are consecutive

= `18/(""^20C_3)`

= `18/((201)/(3!17!))`

= `(18*3!*17!)/(20!)`

= `(18 xx 3 xx 2 xx 17!)/(20 xx 19 xx 18 xx 17!)`

= `(3 xx 2)/(20 xx 19)`

= `3/190`

∴ P(three numbers are not consecutive) = `1 - 3/190 = 187/190`

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पाठ 16: Probability - Exercise [पृष्ठ २९९]

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एनसीईआरटी एक्झांप्लर Mathematics Exemplar [English] Class 11
पाठ 16 Probability
Exercise | Q 19 | पृष्ठ २९९

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