Question

When you boot up a computer and hear a single beep, but the screen is blank, what can you assume is the source of the problem?

Answer 1

either your screen isnt plugged in and synced properly or you have a problem in the automatic boot system 

Answer 2

The monitor or monitor cable.

Step-by-step explanation:

If the CPU actually turns on and you can hear a beap, the problem could be with the monitor or the monitor cable, it might not be well connected to the CPU or the power chord could be misscontacting, so in that case you should reconnect it properly, that could be the mos logical thing to assume is the problem.