An ideal transformer with purely resistive load operates at 12kV on...

The given data is

$P = 60 \times {10}^{3}W$

${V}_{s} = 120V$

A transformer has a primary coil and a secondary coil.

The formula for the power delivered is given by

$P = \dfrac{{V}^{2}s}{{R}_{s}}$

$⇒ 60 \times {10}^{3} = \dfrac{120 \times 120}{{R}_{s}} ⇒ {R}_{s} = \dfrac{120 \times 120}{60 \times {10}^{3}} = 240mΩ$