How would I calculate the average age of my survey respondents based on the answer percentage breakdown?

I am working on compiling results for a survey my organization just ran. One of the questions asks about the respondents' age range and here are the results: Under 30 (9%); 30-35 (16%); 36-40 (18%); 41-45 (20%); 46-50 (15%); 51-55 (12%); 56 and older (11%). How can I use these figures to calculate an average age for the respondents? It doesn't need to be super exact (and it really can't be, considering the vague nature of the "Under 30" and "56 and older" designations), but something close would be great.

How would I calculate the average age of my survey respondents based on the answer percentage breakdown?
If the survey was for adults only, one way would be to add the sum of the means times percent represented ,


(age 24 X .09) + ( 32.5 X .16) + ( 38 X .18) + (43 X .20) + ( 48 X .15) + ( 53 X .12) + ( assuming the oldest age range surveyed stops at about 75 , as I have had in prior phone survey done, then- 66 X .11) - will give yoiu a rough idea. It would be better if yoiu had medians of age age group, but this is the next best approximation...............


the means are the means of a given age group range , ie 43 is the mean of 41 through 45) Since you dont know individual ages of respondents.
Reply:My initial guess would be that your average age is 41-45, since that is where the largest percentage is, but obviously this is presumptuous. Unless you do have the actual age of those in the survey, you're going to have to use an estimate.





You could assign 1 - 6 to each of the age categories, multiply them by their number of votes and divide by the total number of votes, or multiply them by their percentage number (ex. 9, not .09) and divide that by 100. I would assume that either way you're going to come pretty close to the 41-45 category. I actually tested the percentage way before I wrote this, and that's what I got. Plus, if this is just an estimate, a designation like 41 - 45 should be an acceptable answer. Otherwise, maybe you could say something like 42 and a half.





Hope this helps!
Reply:take all the ages of the people that answered and add them together, then divide by the number of people that answered. this gives you the average.