Question

Suppose a complex of apartments has 3 floors with 70 apartments in total while the first floor has one more apartment tha the secondfloor.If I live in the third floor and a new tenant has just moved in the complex.What is the probability that he has lease an apartment in the same floor with me.Furthermore there is knowledge about tenants to the right and to the left of my apartment.

Answer 1

There are 70 apartments in total with 3 floors. So the number of apartments each floor has are:

Floor 1: 24

Floor 2: 23

Floor 3: 23

You live in the third floor and you have knowledge about the tenants to the right and left of your apartment, hence it means that the new tenant is not in these three apartments. He can be in the remaining (23 - 3) = 20 apartments on the third floor OR (24 + 23) = 47 apartments on rest of the floors.

The number of apartments in which the new tenant could have moved = 20 + 47 = 67

The number of apartments on the third floor in which the new tenant could have moved = 20

The required probability can be calculated as: 20/67 = 0.298