[skyyler]

Your rule of thumb is wrong a third of the time which is a D grade.

Technically passing, I suppose.

[input_sh]

Yes, that's what rule of thumb means.

It doesn't imply it's always the case, just more often than not. >60% is more often than not.

[skyyler]

I think you're a bit off on what rule of thumb means. Something that's false 1 out of 3 times is not "generally true".

If it was a 51/49 split in probability would you still call it a rule of thumb?