"Five persons entered the lift cabin on the ground   floor of an 8-floor house. Suppose that
Channel: Doubtnut
Date: 2020-07-12

"Five persons entered the lift cabin on the ground
 
  floor of an 8-floor house. Suppose that each of them independently and with
 
  equal probability can leave the cabin at any floor beginning with the first.
 
  Find out the probability of all five persons leaving at different floors."