The power produced by the horse can be calculated using the formula:
Power = Work done / Time taken
Given that the horse produces 1250000 J of work when it pulls the wagon, we need to find the power produced by the horse when it pulls for 20 seconds.
Power = 1250000 J / 20 s
Power = 62500 watts
Therefore, the horse produces 62500 watts or 62.5 kilowatts of power when it pulls the wagon for 20 seconds.