Question

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

Answer 1

5 students are to be selected from 11 students

When 2 specified students are included then remaining 3 students can be selected from (11 – 2) = 9 students.

∴ Number of ways of selecting 3 students from 9 students = ⁹C₃

= `(9!)/(3! xx 6!)`

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

= 84

∴ Selection of students is done in 84 ways when 2 specified students are included.