The short-run total cost curve (TC_SR) for Ivor’s Engines is constructed using the isocost lines from the expansion path in Figure 7.5. At Y, when Q = 20, TC_SR and the long-run total cost curve (TC_LR) overlap. At all other values of Q, including Q = 10 and Q = 30, TC_SR is above TC_LR, and short-run total cost is higher than long-run total cost. This is also true when Q = 0 since some input costs are fixed in the short run, while in the long run, all inputs are flexible.