What do people do if they don't make Physics and Chem? Do they just choose Bio or somethingYou need to be top 188 (out of 216) to do Maths Ext. 1, but by year 12 that number will drop to 164. Top 80 in our year do the 2u maths advanced course this year.
Top 144 make Physics and Chemistry, but anyone can do Biology because its not as popular. For other subjects, yeah there are no benchmarks unless you really screwed up in that subject. I'm happy I made all of my subjects and they fit on my timetable, at least!