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प्रश्न
Five students are selected from 11. How many ways can these students be selected if two specified students are not selected?
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उत्तर
Number of students is 11. We have to select 5 students
2 particular students are not selected:
If 2 particular students are not selected, then from remaining (11 – 2) = 9 students, we have to select 5 students.
This can be done in 9C5 ways.
∴ total number of selections
= 9C5
= `9/(5!4!)`
= `(9 xx 8 xx 7 xx 6)/(1 xx 2 xx 3 xx 4)`
= 126.
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