The EST (Prescreen test) is only an indicator of how you will do on the ASVAB. I have seen people get in the 40's on the EST and bust out a 70 on the ASVAB, then again I have seen it go the other way too. A number of factors will figure into your qualification as a non high school graduate including, but not limited to, your age, work history, ASVAB score and police involvement. More than likely your Recruiter wants to put you in as bad as you want to be in. 15 semester hours of college (100 level classes and above) places you in the HSDG (high school diploma graduate) category and reduces the scrutiny placed on you.