What I am doing is taking the Kaplan practice tests and looking at my score report after I complete it and compare it to the students who posted their subsection and composite scores who took the latest PCAT. This is probably not 100% accurate but it may give a general idea of how many you'd need to get right. For Bio I got a 450 on the kaplan practice test (which I think was about 36/48 right?) and it came out to be around 90th %ile. The scores may differ because you have to take into account that the experimental questions are not really stressed on the Kaplan tests.