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if n persons are seated in row the number of ways of selecting 3 so that no two r seated next to each other

if n persons are seated in row the number of ways of selecting 3 so that no two r seated next to each other


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1 Answers

Anil Pannikar AskiitiansExpert-IITB
85 Points
11 years ago

Dear Shiwani,

 

Required Prob,  = select 3 persons from n  -  consider 2 persons sitting together as one so total persons are n-1 and now select 3 persons from n-1

                      =  nC3 - (n-1)C3*2

 

Note : (n-1)C3*2 bcoz 2 persons can be arranged in two ways .

 

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Askiitians Expert

Anil Pannikar

IIT Bombay

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