Question

Five students are selected from 11. How many ways can these students be selected if two specified students are not selected?

Answer 1

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.