i am studying statistics and operations research double major in canada. although i don't know about the requirement of entering a math program in hk , i want to recommand u to have a look with a program called "operations research" in hku (
http://hkumath.hku.hk/web/teaching/BSc_II_III_07.pdf ). the three major components of the discipline of operations research are Optimization, Statistics, and Computer Science
quoted from the University of Waterloo: "Operations Research is the field of mathematics that deals with the problems of management in business and government. It involves constructing mathematical models of complex real world situations and then applying sophisticated techniques to these models in order to make optimal, or near optimal, decisions."
comparing statistics, operations research is more practical in hk. if u like stats,u would like OR either.