$1.$ A $25-$kVA, $2300/230-$V$,$ single transformer has a high$-$voltage winding with a resistance of $1\mathrm{.}5$ and a leakage reactance of $2\mathrm{.}4.$ The low$-$voltage winding has a resistance of $0\mathrm{.}015$ and a leakage reactance of $0\mathrm{.}024.$ Find the following: a$)$ Voltage regulation of the transformer for full load at $230$ V and $0\mathrm{.}866$ power factor lagging. b$)$ The efficiency of the transformer under the conditions of part $($a$).40$ pts$.$