JEE Main20206 Sep 2020Morning ShiftMathematicsPermutation and CombinationActual
Two families with three members each and one family with four members are to be seated in a row. In how many ways can they be seated so that the same family members are not separated ?
Options
- A2 !   3 !   4 !
- B( 3 ! ) 3 · ( 4 ! )
- C  ( 3 ! ) 2 . 4 !
- D 3!  4 ! 3
Correct answer
B. ( 3 ! ) 3 · ( 4 ! )
Step-by-step solution
We will use the concept 'objects are together'   3 !  ⏟ Total 3 families × 3 ! 2 ⏟ families with all 3 members together ×   4 !  ⏟ family with all 4 together = ( 3 ! ) 3 × 4 !