Answer
The lady is behind door #2
Work Step by Step
Door 1) In this room there is a lady,and in the other one there is a tiger
Door 2) In one of these rooms, there is a lady, and in one of them there is a tiger.
We know 1 sign is true and the other one false.
If the sign on door 1 is true, then the sign on door 2 is also true.
On the other hand, if the sign on door 1 is false, the second one is still true.
Therefore, the tiger is in room 1, and the lady is in room 2.
