Question

1300. Watts enter a transformer with 900.0 Volts. If 1.500 A is needed how many volts will exit the transformer?

Answer 1

$I_p\cdot U_p\approx I_s\cdot U_s\to P_p\approx1.5U_s\to U_s\approx P_p/1.5=1300/1.5=867(V)$