Question

# How many signals can be given by means of 10 different flags when at a time 4 flags are used, one above the other?

^{10}P_{4}
^{10}C_{4}
- 4
- 40

^{10}P_{4}^{10}C_{4}Hint:

**Use formula**

## The correct answer is: ^{10}P_{4}

### You are given 10 flags of different colors and you can give signals, but use only 4 flags.

First you have to choose 4 flags from 10 flags

This can be done in ways

Among this 4 flags of different colors, 4! ways of different arrangements are possible

So total number of signals =

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