In reply to florence58: Its impossible to say..
Jura is 16 miles and only a small % manage it in 4 hrs, which is 15 min miling..
Many others will be around 7-8 min miling.
Somebody has to come last as they say.. just go out and try a short race, see where you come. Then have a google/race results of those around you or ask them how they do and build up the race distances...