Cbse class 11 PERMUTATION
EXAMPLE7 Five persons entered the lift cabin on the ground floor of an 8-floor house. Suppose
each of them can leave the cabin independently at any floor beginning with the first. Find the
total number of ways in which each of the five persons can leave the cabin (i) at any one of the
7 floors (ii) at different floors.
SOLUTION Suppose Aj, Az, A3, Ay, As are five persons. (i) A, can leave the cabin at any of the
seven floors. So, A, can leave the cabin in 7 ways. Similarly, each of Ay, A3, Ay, As can leave the
cabin in 7 ways. Thus, the total number of ways in which each of the five persons can leave the
cabin at any of the seven floors is 7x 7x7x7x7
0
