Very good Idea w the Radio.
Good thinking.
Larry sed - "My guess is that there is an outlet or two on that circuit between the dead outlet and the breaker box and the circuit has opened up at the dead outlet or the one just upline from it."
Yup., well explained.
WHERE in the house are these recepts?
I still wanna make positive they are not off a GFI.
IF it is not a tripped GFI issue, then your problem highly probable is in.........the closest to these three other recept that is hot, or.. in the dead recept closest to the closest hot one, as per Larry.
And so it's a poor connection like said above, very likely a backstab as Wylie said.
If you are not used to going into boxes, You COULD start by first finding the closest hot and the closest dead one to each other, and plug in a tight fitting 3 wire cord into them, put a small reasonable sideways wiggle on the cord end.. WHILE your power is on and you know the radio is "On" and loud.
You very well may get radio action, found the box w the loose connection.
Obviously, the faster the radio puts out after being energized, the better for this.
If it not fast, plug in a lamp w fast on old school lightbulb in it you can see.
Anyway, it would help us to know - Approx age of house... WHERE..what room these are in. Marc