Answer to Question #149687 in Discrete Mathematics for im nayeon

Question

Five different colored flags can be hung in a row to make a coded
signal. How many signals can be made if a signal consists of the display of one
or more flags?
A. 11
B. 13
C. 15
D. 17

Answer 1

We can apply binary system for calculations.

Let 1-is flag, 0- no flag.

The we can represent coded signal with binary numbers:

from 00001 to 11111

Answer: C.

$N=2^4-1=15$