Question

5 flags of different colours how many different signal can be generated in single requires the use of two flags one below the other

Answer 1

here the total flags are =5

we have to generally use only two flags one below the other .

1st case:- in standing of first flag ,we use any of the flag out of 5. so we have total of 5 ways to generate signal.

2nd case:- in standing another flag below the other, we does not use that flag used in 1st case .the flag used in 1st case is any one of the five flags .so we use any of the {5-1} flags. so total ways of using flags one below the other is 4

by fundamental principal of counting ,

                 = 5×4=20

so 20 different signal can be generated