$[$W$]$ In your analysis, you assumed that all spiral galaxies are the same physical size $=70$ kly $.$ In reality, spiral galaxies aren't all the same size: the average galaxy size is $70$ kly$,$ and their sizes vary by some amount about this average value. In what way does the standard ruler assumption $($assuming that all galaxies are the same size$)$ affect your measurement of the Hubble constant? Hint: think about what would happen to your distance estimate for a single galaxy if its physical size was in fact smaller or larger than the size you assumed, then imagine this is happening randomly for all galaxies $-$ what would your graph look like then?