How do I generate random numbers in such range with matlab?

I want to generate some random numbers, that is for such distribution,

10% of them are in Catagory A (T = 6),

40% of them are in Catagory B (T = 8),

40% of them are in Catagory C (T = 10),

10% of them are in Catagory D (T = 12).

I just started to learn matlab and I tried rand(x) and randn(x) but it seems neither of them can do that?