<p>Just to add a bit to ReneeV's post, it's true that strong math skills tend to correlate to good theory skills. </p>
<p>The AP course, even with a 5 or 4, will not place you out of first level theory in virtually any undergrad music program. The AP program is good background for self teaching if not offered in a local hs program, as prep for basic or expanded knowledge in preparation for audition based programs theory placement testing.</p>
<p>This testing is the norm, and will also include an aural skills level assessment, and potentially a piano/keyboard assessment test as well. Please note these tests are placement tests and are not normally part of undergrad admissions decisions (although can be at the grad level).</p>
<p>The tests are used to determine 1st year initial course level in the 3 areas mentioned, and some schools give them at audition, some after matriculation as part of orientation. Many students, even those with high levels of theory background end up in theory 101, at programs from Podunk U to Juilliard.</p>
<p>A 5 on the AP theory may get you credit as an elective against total degree required credits, but will not offset a required music course. </p>
<p>Realize it is important, but once you're in, not as part of an admissions decision. There's often a supplementary level theory class ("theory 100") for those with skill levels below the school's "theory 101" threshold, as there are for ear training and piano.</p>