Hi there! First of all, I’d like to state that colleges like Columbia are not ‘mid-range to slightly high range’, these colleges are some of the absolute best, most elite and most selective colleges in the US and world.
Subjects:
Yes, business subjects could decrease your chances. If you decide to apply to universities like Caltech, you’ll need to take SAT Subject Tests in the sciences. Not taking science subjects for your A-levels will therefore hurt you, as you’ll most likely get lower scores, which decrease your chances. However, if the colleges do not demand you take science SAT Subject Tests, it probably won’t matter, as long as you do well in the SAT Subject Tests that you do take.
Scores:
Your IGCSE scores, if you have to submit them, will hurt you extremely much, to be honest. Anything below A/A* will hurt, actually. About your A-levels: honestly, 3As and 1B or 2As and 1B will also hurt, a lot, especially because of your poor IGCSE results. These colleges expect AAA-like scores. An SAT score of 1400+… That depends on the +. Usually, it’s good to have a score of >1500, but students also get accepted with scores of 1300-1450 if they have great honors/awards, letters of recommendation etc. For more information about scores:
Moreover, scores alone won’t get you admitted: you need extracurriculars. Lots of people with perfect grades, GPAs, SAT scores, SAT Subject Test scores etc. get rejected, every year. If your extracurriculars are absolutely flabbergasting you may have a shot, but your IGCSE grades will hurt a lot, and so will your A levels, if you get Bs. However, it’s not absolutely chanceless.
Good luck with your application!
PS Tip: ‘as well as many extracurriculars’, #neverforget: quality over quantity. Try to do extremely well in some, instead of doing just a little bit in every 