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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?
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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