Question
Mathematics Question on permutations and combinations
A sports team of 11 students is to be constituted, choosing atleast 5 from class and atleast 5 from Class If there are 20 students in each of these classes, in how many ways can the team be constituted?
A
20×20C5
B
20C5×20C6
C
2×20P5×20P6
D
2×20C5×20C6
Answer
2×20C5×20C6
Explanation
Solution
No. of students in each class =20 We have to select atleast 5 students from each class. ∴ No. of selection of sports team of 11 students from each class is given in following table. ∴ Total number of ways of selecting a team of 11 players =(20C5×20C6)+(20C6×20C5) =2×20C5×20C6