Question

Five students are selected from 11. How many ways can these students be selected if two specified students are selected?

Answer 1

Number of students = 11
Number of students to be selected = 5
Here, 2 specified students are included.
So, we need to select 3 more students from the remaining 9 students.
This can be done in:
= `""^9"C"_3`

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

= 84 ways
∴ Number of required selections
= 84 × 1 × 1
= 84
Thus, 84 selections. can be made such that 2 specified students are included.