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There are seven empty seats in a theater, and four customers need to find places to sit. How many different ways can these four seat themselves g

User Gev
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1 Answer

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Answer: 840

Explanation:

Given : The total number of empty seats in the theater = 7

The number of customers need to find places to sit = 4

Since here order of their sitting matters , then we use permutation to find the number of ways of sitting.

The number of permutations of n things taking r at a time is given by :-


^nP_r=(n!)/((n-r)!)

Then , the number of permutations of 7 things taking at a time is given by :-


^7P_4=(7!)/((7-4)!)\\\\=(7*6*5*4*3!)/(3!)=840

Hence, the number of different ways can these four seat themselves = 840

User Scottlittle
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