For just starting out that's a good pace. If you know you're getting a good workout then you're doing great. As you become stronger and more effecient at your cycling you'll see your average go up.
When I first started cycling my average was around 9-10 mph. We live in a very hilly community and it's a workout every time I get on my bike. It's hard to get a recovery ride because I either have to ride much slower (because of the hills) or drive to a place that's more level so I can do a speed ride. Now I can average 12-15 in the hilly areas and 15-18 on the flat.
Keep doing what you're doing!!! You're doing great!
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