A lift with 7 people stops at 10 floors. People varying from zero to 7 go out at each floor. The number of ways in which the lift can get emptied, assuming each way only differ by number of people leaving at each floor, is_______.
11440
Let us take Ai number of persons gets out of lift at ith floor.
A1+A2+A3+.........A10=7
This problem is similar to distributing 7 people among 10 floors.
It can be done = 7+10−1C10−1 = 16C9 = 16C7