Question

A lift in a building starts with 7 passengers and stops at 10 floors.if each passenger is equally likely to get off at any floor and all passengers leave independently.what is the probability that atleast two passengers will get off at the same floor?​

Answer 1

Answer:

Correct option is

C

10

5

10P

5

Total ways in which one passenger can stop =10

Total ways in which 5 passengers can stop =10∗10∗10∗10∗10

=10

5

We will select 5 floors from 10 floors and assign each individual to each floor to keep everyone isolated from each other

No. of ways in which no two persons stop at the same floor =10C

5

∗5!

=10P

5

⇒P(E)=10P

5

/10

5