T-shirt manufacturer is planning to expand its workforce. It estimates that the number of T-shirts produced by hiring x new workers is given by T(x) = -0.25x+3x3,0x9. When is the rate of change of T-shirt production increasing and when is it decreasing? What is the point of diminishing returns and the maximum rate of change for T-shirt production? Graph T and T' on the same coordinate system. The rate of change of T-shirt production is increasing on (Type your answer in interval notation.)