SUAD Alwin the purchasing agent for Dubai airlines has determined that the second plane took $18,000$ hours to produce using an $85\%$ learning curve in a $$40$ per hour labor charge he wants to determine the cost of the four additional planes time required for the fourth unit equals $15,300$ hours cost of the fourth unit equals $$612,000$Time required for the fifth unit equals $14,520$ cost of the fifth unit equals $$580,800$ time required for the sixth unit equals