What to consider in making major assumptions in marketing aspect?

Even though I am not very good in marketing, I will try to briefly provide my humble opinion...

Marketing is: "wrap up your product into a nice package, in order to attract the potential buyer's attention".

The assumptions in marketing aspect therefore, should therefore be answering the "WHAT" (product) "WHEN" (time) "WHERE" (Country/location), "TO WHOM" (client) and "FOR HOW LONG" (duration) questions.

Try selling your mobile phone to your grandfather, who is a high school graduate in Africa and try to sell the same phone to a university student in USA...