Question

The number of signals that can be made with 3 flags each of different colour by hoisting 1 or 2 or 3 above the other is

• A. $3$
• B. $7$
• C. $15$
• D. $16$

Answer 1

The correct option is C $15$

Number of signal that can be made,

$\Rightarrow$ Using flag $1$ is ${}^3{P}_1=3$

$\Rightarrow$ Using $2$ flags ${}^3{P}_2=6$

$\Rightarrow$ Using $3$ flags ${}^3{P}_3=6$

So, total signed $3+6+6$

$=15$

Hence, the answer is $15.$