11 persons are sittingin a row. how many ways can 11 persons be arranged in a row such that 3 persons should always be together?  Choices:	A) 7!×2!	B) 10!×1!	C) 9!×3!	D) 8!×2!	E) 6!×3!
Given that three particular persons should always be together. Hence, just group these three persons together and consider as a single person.   Therefore we can take total number of persons as 9. These 9 persons can be arranged in 9! ways.   We had grouped three persons together. These three persons can be arranged among themselves in 3! ways.   Hence, required number of ways   =9!×3!   9!×3!
<result>C</result>
11 persons are sittingin a row. how many ways can 11 persons be arranged in a row such that 3 persons should always be together?