anil i agree with you.
But i think to know the full load losses you have to go for open ckt test (i.e. iron losses) and short ckt test (i.e copper losses).then to know tfransformer loss at any load= iron loss + copper loss at that load.
e.g. copper loss at 50% load = ( 50% 0f full load current)2*R
=(I/2)2*R
=I2R/4