How fast should 42 year man run a 5k?

I was looking up the same question. I started training in the spring and just timed myself this morning for the first time. I want to run my first 5k next Saturday. I did 3.5 miles in 34 minutes 12 seconds. I was slightly disappointed in myself but now I know my time and can continue to work on improving. I have been looking at other sites and have set a goal of 30 minutes for being female and age 42.