Since the Power is directly proportional to the velocity, their ratio

is constant.
<span>Therefore </span>

which is a proportion:
500 : 1000 = x : 1728
that can be easily solved:
x = (500×1728)/1000 = 864kW

64% of 75 tiles is 48 tiles.
Changing the order may not affect the answer in some situation, however it's not a rule.