AP EAMCET202119 Aug 2021Evening ShiftMathematicsPermutation and CombinationActual
In how many ways can 9 examination papers be arranged so that the best and the worst papers are never together?
Options
- A9 ! − 2 ! × 7 !
- B9 ! − 2 ! × 8 !
- C9 ! − 8 !
- D9 ! − 7 !
Correct answer
B. 9 ! − 2 ! × 8 !
Step-by-step solution
The number of ways in which 9 papers can be arranged are 9 ! ways. Take Best and Worst papers as one unit then, 9 - 1 ! = 8 ! The best and worst papers can arrange themselves in 2 ! ways. Total number of ways = 9 ! - 2 ! × 8 !