Question

Question 9 In how many ways can a student choose a programme of 5 courses if 9 courses are available and 2 specific courses are compulsory for every student?

Class X1 - Maths -Permutations and Combinations Page 153

Answer 1

This is your answer, check it

Answer 2

Here, total number of available courses = 9
we have to choose 5 courses from 9 course . but there are some conditions:
2 courses are compulsory for every students .hence, we have to choose only 3 courses instead of 5, out of 7 courses instead of 9.

hence, student have to choose out of 3 courses instead of 7 .
hence, total number of ways = 7C3
= 7!/3!(7-4)!
= 7×6×5/6
= 35 ways