@Rahul Shah, do your frames have one or two dimensions? I will assume you mean 2D frames. Let's assume each frame is 32x32. The mean and s.d. you have specified will cause some array values to be negative. If the values represent image intensities, then negative values are non-sensical, and you should adjust the mean and SD accordingly.
mn=40;
sd=25;
A=mn*ones(32,32,20)+sd*sqrt(12)*(rand(32,32,20)-0.5);
B=reshape(A,[32*32*20,1]);
fprintf('A: mean=%.3f, s.d.=%.3f, min=%.3f, max=%.3f\n',mean(B),std(B),min(B),max(B));
A9=A(:,:,9); %frame 9
histogram(A9)
image(A9)
Try.
