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A committee of 7 has to be formed from 9 boys and 4 girls. In how many ways can this be done when the committee consists of: at least 3 girls? - Mathematics

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प्रश्न

A committee of 7 has to be formed from 9 boys and 4 girls. In how many ways can this be done when the committee consists of: at least 3 girls?

योग

उत्तर

If there are at least 3 girls in the committee then the committees will be formed as follows:

  1. 3 girls, 4 boys
  2. 4 girls, 3 boys

Total ways of forming these committees = 4C3 x 9C4 + 4C4 x 9C3

= 4C1 x 9C4 + 1 x 9C3

= `4 xx (9 xx 8 xx 7 xx 6)/(1 xx 2 xx 3 xx 4) + (9 xx 8 xx 7)/(1 xx 2 xx 3)`

= 504 + 84

= 588

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अध्याय 17: Combinations - Exercise 17.2 [पृष्ठ १७]

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आरडी शर्मा Mathematics [English] Class 11
अध्याय 17 Combinations
Exercise 17.2 | Q 30.2 | पृष्ठ १७

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