Anyway, I asked respondents their ages, they answered as follows:

16 or under (7)

17-25 (20)

25-30 (9)

30 or older (2)

Decline (23)

Total 61

So, is it possible (with the data grouped in this fashion) to calculate the average age?? If so, how?

And if it is possible, how do I interpret this data (if its in a percentile or something)?

It has been a long time since i have done maths, and I have totally forgotten this stuff!