GrindCо is а smаll firm thаt prоduces custоm skateboards. The owner has carefully tracked costs and determined that the firm’s total cost (TC) of producing q skateboards per week is: TC = 0.05q3 - 5q2 + 400q + 800. The marginal cost (MC) of production is given by: MC = 0.15q2 - 10q + 400. GrindCo wants to operate efficiently and is especially interested in minimizing its average variable cost (AVC) to remain competitive on price. At what level of output, q, is AVC minimized?