I agree with Bawaqar...If you want answers to your questions, I suggest you go to the Ministry of Commerce and ask there how many grocery shops are registered in Doha, How many supermarkets? I think you forgot bakeries too, they're the one's making the Khubbus, you know. Then inquire from one bakery, how many Khubbus they make in a day. Then all you have to do is multiply and make your calculations.
If you are thinking to go into business, you have to do a business study and you have to go out of your way to know the answers to your questions. Mostly, you have to research, pal? Good luck and go out there!!