You are quite right about not being able to predict the age range on singles groups. Traditionally, singles that have come to us in the past have been late 20's - early 30's. Our singles group this summer is just the opposite, mid-30's to mid-50's! I guess single Baby Boomers are ready for some relaxation and fun!
The best advice is to just ask the person handling the cruise what the age range is for the folks who are booked on the cruise.
Hope this helps!