numerical question-electrical engineering

I estimate these are in fact homework questions.

you are right sir,but being in field it sometimes becomes difficult to answer theoritical questions?i hope to find some professors

Unfortunately even if these were just theoretical questions, they cannot be answered without more information (unless a number of assumptions are made).

1)front 20mx50m of a concrete building in an industrial town is to be illuminated by projectors fixed on ground 50m away from the building.estimate the number and size of the same

What level of lux is required as it depends on application and what lighting standard you are designing to?

What type of lights and fixtures, there is a great deal to choose from?

etc

In the end this is STILL homework based on something you should have the necessary background to answer.