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In how many ways can 7 people line up at a ticket window of a cinema hall?

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Best answer

To find: number of arrangements of 7 people in a queue.

Here there are 7 spaces to be occupied by 7 people. 

Therefore 7 people can occupy first place.

Similarly, 6 people can occupy second place and so on.

Lastly, there will be a single person to occupy the 7 positions. 

Formula:

Number of permutations of n distinct objects among r different places, where repetition is not allowed, is

P(n,r) = n!/(n-r)! 

Therefore, permutation of 7 different objects in 7 places is 

P(7,7)  = \(\frac{7!}{(7-7)!}\)

\(\frac{7!}{(0!)}\) = \(\frac{5040}{1}\) = 5040.

Therefore, the number of possible ways is 5040

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