Kindly explain

4. Assume that a firm's total cost of producing an output of 600 units is currently $24 000. If total cost increases to $48 000 and the price of inputs and technology remain unchanged, calculate the change in average cost, and state whether constant returns and economies or diseconomies of scale exist for each of the three cases: a) Output increases to 1100. b) Output increases to 1250. c) Output increases to 1200