If you are going to attend one of an open day with Qatar Airways, you should bear on your mind that the most important thing for them to accept you as a cabin crew is the shine on your eyes.
They do not expect from you to answer the all specific questions on a professional way.
They just want to know that whether you are able to be a cabin crew(Reaching 2.10 metres on your toes, no tattoo ) and want to work with Qatar Airways.
If you have the ability to impress people by your desire of being a cabin crew with Qatar Airways,then you are also able to impress the Human R. managers at the interview.

Good Luck!