Question

find the number of different signals which can be given with 5 flags of different colours placed one above the other, by using atleast two flags?

Answer 1

To find the number of different signals that can be given with 5 flags of different colors placed one above the other, we need to consider all possible combinations of flags.

Since we need to use at least two flags, we cannot use just one flag. Therefore, we can start by considering the number of ways to arrange the 5 flags in groups of 2 or more. We can then add up all these possibilities.

1. Arrangements of 2 flags:
- There are 5 choices for the first flag, and 4 choices for the second flag (since we cannot repeat the same flag).
- Total number of arrangements of 2 flags = 5 * 4 = 20.

2. Arrangements of 3 flags:
- There are 5 choices for the first flag, 4 choices for the second flag, and 3 choices for the third flag.
- Total number of arrangements of 3 flags = 5 * 4 * 3 = 60.

3. Arrangements of 4 flags:
- There are 5 choices for the first flag, 4 choices for the second flag, 3 choices for the third flag, and 2 choices for the fourth flag.
- Total number of arrangements of 4 flags = 5 * 4 * 3 * 2 = 120.

4. Arrangements of 5 flags (using all flags):
- There is only 1 option for arranging all 5 flags in a specific order.

To find the total number of different signals, we sum up the arrangements from each category:
Total = Arrangements of 2 flags + Arrangements of 3 flags + Arrangements of 4 flags + Arrangements of 5 flags
Total = 20 + 60 + 120 + 1
Total = 201.

Therefore, there are 201 different signals that can be given using at least two flags.