A producer of hard disk drives has a short-run total cost curve given by STC(Q) = K

Question:

A producer of hard disk drives has a short-run total cost curve given by STC(Q) = K + Q2/K . Within the same set of axes, sketch a graph of the short-run average cost curves for three different plant sizes: K = 10, K = 20 and K = 30. Based on this graph, what is the shape of the long-run average cost curve?