A 2.0kW transformer operates at full load under the following conditions.
a. (i) Before modification: copper loss =120W, core loss =80W. Calculate its full-load efficiency.
b. (ii) After modification: the copper loss is reduced by 20% while the core loss remains the same. Calculate the new full-load efficiency.
c. (iii) Find the percentage increase in efficiency due to the modification (answer to one decimal place).