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Let Pn denotes the number of ways in whi...

Let `P_n` denotes the number of ways in which three people can be selected out of 'n' people sitting in a row, if no two of them are consecutive. If `P_(n+1)- P_n=15` then the value of 'n` is____.

Text Solution

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The correct Answer is:
8
`.^(n-1)C_(3)-.^(n-2)C_(3)=15`
`impliesn=8` `[becauseP_(n)=.^(n-2)C_(3)]`
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