Answer:
2000 W
Explanation:
First of all, we need to find the output voltage in the transformer, by using the transformer equation:

where here we have
V1 = 200 V is the voltage in the primary coil
V2 is the voltage in the secondary coil
N1 = 250 is the number of turns in the primary coil
N2 = 500 is the number of turns in the secondary coil
Solving for V2,

Now we can find the power output, which is given by
P = VI
where
V = 400 V is the output voltage
I = 5 A is the output current
Substituting,
P = (400 V)(5 A) = 2,000 W