Given 5 flags of different colours, how many different signals can be generated if each signal requires the use of 2 flags, one below the other?

Solution:

A signal can have only 2 flags. The total number of flags available is 5. So
No. of ways of choosing first flag = 5
No. of ways of choosing the second flag = 4
By fundamental counting principle, 
Therefore, total possible number of ways = 5×4 = 20

NCERT Solutions Class 11 Maths Chapter 7 Exercise 7.1 Question 6

Given 5 flags of different colours, how many different signals can be generated if each signal requires the use of 2 flags, one below the other?

Summary:

Given 5 flags of different colours, the number of different signals that can be generated if each signal requires the use of 2 flags, one below the other is 20