LEARN BY EXAMPLES: 

Eight people Aarush, Bindu, Chunnu, Divya, Etti, Prithvi, Gopal and Harish live in an eight storey building, but not necessarily in the same order. The lowermost floor is numbered 1 and the topmost floor is numbered 8.

Aarush lives on an even-numbered floor but not on the floor numbered second or fourth. Only three floors are there between Aarush and Bindu. Only two people live between Chunnu and Etti. Prithvi lives on a floor above Divya. There are equal numbers of floors between the floors on which Etti and Bindu live and between the floors on which Aarush and Etti live. Harish lives immediately below Divya’s floor. Gopal lives immediately below Aarush’s floor.

Common explanation:

Reference:
Aarush lives on an even-numbered floor but not on the floor numbered second or fourth.
Only three floors are there between Aarush and Bindu.
Gopal lives immediately below Aarush’s floor.

Inference:
 

Reference:

There are equal numbers of floors between the floors on which Etti and Bindu live and between the floors on which Aarush and Etti live.
Only two people live between Chunnu and Etti.

Inference:

Here, Case 1 splits into two more cases:
 

 
Reference:

Harish lives immediately below Divya’s floor.
Prithvi lives on a floor above Divya.

Inference:
 

Case 1 A fails here as there is no such place to accomodate Harish and Divya.

Case 1 B fails here as it violates the second condition where Prithvi lives on the floor above Divya.
Thus, we get case 2 as our final arrangement.