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  • How many different signals can be generated with 7 flags of various colors if each signal requires the use of 4 flags stacked one below the other?  <div class='qna-opti

How many different signals can be generated with 7 flags of various colors if each signal requires the use of 4 flags stacked one below the other?

 

Option: 1

360


Option: 2

840


Option: 3

420

 


Option: 4

530


Answers (1)

best_answer

Each signal needs two flags.

Thus, the number of possible signals produced is given by,

\begin{aligned} &{ }^7 P_4=\frac{7 !}{(7-4) !}\\\\ &{ }^7 P_4=\frac{7 !}{3 !}\\\\ &{ }^7 P_4=\frac{7 \times 6 \times 5 \times 4 \times 3 \times 2}{3 \times 2}\\\\ &{ }^7 P_4=840 \end{aligned}

Therefore, the different number of signals generated is 840.

 

Posted by

Gaurav

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