To keep your options open, I suggest you take Pure Maths with Statistics 1 and 2 as your secondary exams. In this manner, you will have a fairly good knowledge of statistics and at the same time, will have excellent math skills. This may seem useless if you're going for accounting but more often than not, entry tests involve a lot of fundamental Math and though it seems like a piece of cake, if you're out of touch with basic algebra and geometry for two good years, you'll need a lot of practice. As a Pure Mathematics student I felt an edge over my non-Math and even Further Mathematics students when it came to maneuvering simple entry test questions--I never studied for them and Alhamdullilah, I've sat through at least five tests till now and aced at least four of them.
Other than that, you'll have the option to go into fields besides ACCA too. With Statistics you diminish your chances of holding your ground in Economics and the like; you might be sure of what you want right now, but in practical life nothing is a straight path. You have to go past hurdles and sometimes spontaneous changes, like switching between departments in the same firm because of downsizing. A vaster experience with Math will give you an edge.
