Calculate mean from newly created variable

[Anna weel]

Hello everyone,
I'm new here to this forum and a newbe with Stata. I'm currently writing my thesis and already run into issues.
. tab b05

Age | Freq. Percent Cum.
------------+-----------------------------------
10 | 41 7.12 7.12
11 | 63 10.94 18.06
12 | 46 7.99 26.04
13 | 64 11.11 37.15
14 | 74 12.85 50.00
15 | 60 10.42 60.42
16 | 65 11.28 71.70
17 | 67 11.63 83.33
18 | 60 10.42 93.75
19 | 36 6.25 100.00
------------+-----------------------------------
Total | 576 100.00

I have dataset with a variable b05 that has adolescents in the age groups 10 to 19. Calculating the mean wasn't too hard but I also have to do this for 2 age categories. 10-14 and 15-19. I created with this code "egen age_catjo=cut(b05), at(10,15,22) icodes" the two categories and when I tabulate I see this:
. tab age_catjo

age_catjo | Freq. Percent Cum.
------------+-----------------------------------
10-14 | 288 50.00 50.00
15-19 | 288 50.00 100.00
------------+-----------------------------------
Total | 576 100.00



So far so good. But when I try to take the mean from this I get .5. How do I calculate the mean age in the two different age groups.
Thanks in advance and I probably will have many more questions the coming weeks.

[Nick Cox]

su b05 if inrange(b05, 10, 14) 

su b05 if inrange(b05, 15, 19)

[Anna weel]

Thank you so much.