Okay, answered my own question. Apparently, the average person out for a stroll walks at about 16 minutes per mile, a moderately fit person who walks for exercise would be at around an 11-minute mile, and a very fit "race walker" probably averages a 9.5-minute mile.
Now my mind is wandering, and I'm wondering, from a purely philisophical point of view, how my being on the short side will affect my training - because since my stride is shorter, it takes me more effort (more steps) to walk a mile than, say, my DH who is 6 inches taller than me. It's more work for me to walk a 15-minute mile than for him. Interesting....
Fiona