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A box contains two white, three black and four red balls. In how many ways can three balls be drawn from the box, if atleast one black ball is to be included in the draw

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प्रश्न

A box contains two white, three black and four red balls. In how many ways can three balls be drawn from the box, if atleast one black ball is to be included in the draw

योग
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उत्तर

We have 2 white, 3 black and 4 red balls in a box.

3 balls are to be drawn out of 9 balls atleast one black ball is to be included

So, the possible selection is (1 black and 2 other balls)

or (2 black and 1 other ball)

or (3 black and no other ball)

So, the number of possible selection is

= 3C1 × 6C2 + 3C2 × 6C1 + 3C3 × 6C10

= 3 × 15 + 3 ×6 + 1 × 1

= 45 + 18 + 1

= 64

Hence, the required selection = 64.

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अध्याय 7: Permutations and Combinations - Exercise [पृष्ठ १२३]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 11
अध्याय 7 Permutations and Combinations
Exercise | Q 14 | पृष्ठ १२३

वीडियो ट्यूटोरियलVIEW ALL [1]

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