Answer:
24
Step-by-step explanation:
This problem solution involves permutation to calculate number of arrangements of flags. The reason of using permutation in this scenario is that it is mention in the statement that flags are hanging in a particular order and when order is concern we use permutation. According to permutation definition nPr=n!/(n-r)! and so, the unique signals that are made by using 4 flags are 4P3=4!/(4-3)!=24. Here n=total number=4 and r=number chosen=3.
