According to one site, it's 14: http://moraloutrage.net/staticpages/index.php?page=Arkansas
Some other sites say 16 or 17. You can go to the Arkansas code here http://www.arkleg.state.ar.us/data/ar_code.asp and look at 5-14-103 (rape) and 5-14-110 (sexual indecency with a child) -- looks like its 14 (or "less than 15"). In any case, this was NOT statutory rape (assuming sexual conduct occurred).
I saw many different ages for the age of consent in Arkansas so I just used the oldest.