A step-down transformer reduces the supply voltage from $220 \mathrm{V}$ to $11 \mathrm{V}$ and increase the current from $6 \mathrm{A}$ to $100 \mathrm{A}$. Then its efficiency is

A small town with a demand of $800 \mathrm{kW}$ of electric power at $220 \mathrm{V}$ is situated $15 \mathrm{km}$ away from an electric plant generating power $440 \mathrm{V}$. The resistance of the two wire line carrying power is $0.5 \mathrm{\Omega }$ per km. The town gets power from the line through a $4000-220 \mathrm{V}$ step down transformer at a substation in the town. (a) Estimate the power loss in the form of heat. (b) How much power must the plant supply, assuming there is negligible power loss due to leakage? (c) Characterise the step -up transformer at the plant.