Nitpicking: Does "3x faster" mean at 300%, or at 400%? I would say 300%, but when you say 50% faster I would interpret it as 150%.
It is a expression with no clearly defined meaning, and really shouldn't be used.
It is a expression with no clearly defined meaning, and really shouldn't be used.
It's 300%. If company A is growing 10% every month, and company B is growing 30% a month, people would call B's growth 3x faster (30/10=3).