Hi I am new at this and my father is not available to tell me. I have some little trains that are about 3 " long and the track is 10 mm wide.  Can anybody help me?
They are bachmans

Sounds like N scale to me.

Those are N-scale trains.

Scot

Yea that's what it sounds like, 3" is the same as 40' in N scale for normal Bachmann N scale of 1:160.
Enjoy your trains!
Charles

For Nscale, the tracks s/b 9MM apart. THe tie base will be slightly longer. Nscale is 1/160 of the real RR.