MATLAB: Placing a constant through a column

Question

Imagine this

A=(1:30)';
B=(31:60)';
C=(61:90)';
D=[A B C];
S  = numel(B);
xx = reshape(B(1:S - mod(S, 3)), 3, []);
BB  = sum(xx, 1).' / 3;
F=[A B C BB];

You will notice F is not possible because BB has just 10 variables (Dimensions of arrays being concatenated are not consistent.)

What I need to do is make each value in BB constant for 3 rows so that F can become possible.

Answer 1

repmat(BB,3,1)