So....
to quote you "Worked out the G/S yet?"
Whats the ground speed on the diversion because you need an ETA becuse you may stumble into the CAS beyond your destination.
Whats the Ground speed, No Whizz wheel, no internet application you have 25 hours on a C150 and probably 2 to three hours ground instruction on Nav???
You are using a transposed radial from a VOR that might be 60 miles away on the other side of your map, on your knee , in a cramped cockpit whilst flying the airplane and trying to remember what your instructor said.
I'll say again - complex mental arithmetic in the above situation is prone to error and worse still gross error, he/she might work out the drift to the degree and apply it incorrectly.
Simple concepts: -
Wheres the wind? is it pushing or pulling? therefore am I doing 1, 1.5 or 2 miles per minute.
Where do I want to go? if i point straight at my destination will I be left or right of it therefore will I employ 5 or 10 or 15 degrees of heading change to allow for the drift.
Why complicate matters significantly to get a very small increase in accuracy at the speeds we are discussing.
Accurate well tutored preflight planning is essential but at this level and at these speeds lets just use the principal of kiss