Have you got any metal in the room Betty? The PC I usually use is always about 80% and it's on the floor above and the opposite side of the house.
Or, I suppose, it could be a channel thing
Gadget
The problem is that although wi-fi can travel a mile or more in free air, it doesn't travel through solid objects very well. What happens in a room is that signals get reflected by objects in the room (and the walls themselves), and these reflections come back "out of phase" with the original signals, and they cancel each other out, causing the apparent signal strength to drop. BettyofKent says that she has very little metal in her room, but I bet she has more than she thinks - televison sets, radios, phones, window frames, and the electrical and phone wiring supplying the room - all contain metal ! Of course, the main problem is that wi-fi routers are such horrible ugly things that we all tuck them away out of sight, so we don't see them, and they are rarely in the place where they would work best. I live in an old Fenland farm-house - the external walls are 19" thick double-brick, and the internal walls are 9" thick single brick & plaster. I get such terrible wi-fi coverage in my house that I have two wi-fi networks (one at the front, and one at the back), and both on the same channel incidentally !