Q: Estimate the diameter in kpc of the red-shift=6.56 galaxy at the moment when it emitted light. We're assuming that early galaxies with similar red-shifts have the same number of stars to galaxies as in the present state of the universe. I've taken a look at the small angle formula a = s / d where a = angular size, d = distance and s = galaxy true size (diameter). But for that I need the angular size and distance. I'm not sure if if there is a way to calculate that using the information given in the question. Other than the given information, I have the average density and scale-factor as well.