It is simply a variation
on the normal Rate of Descent formula so there's hardly anything new or extra
to remember.
On a 3 degree Glide Path
Change of Rate of Descent
= Change of Ground Speed x 5
CRoD = -30 x 5 = -150
(You will only be
questioned at 3 degrees)
However, on other Glide
Paths
CRoD = Change GS x 5 x (GP/3)