A torsional helical spring is used to hold a door closed. The handle on the door is located 30 inches from the center of the torsional helical spring. The pull on the handle should be 1 pound when the door is closed and 3 pounds after the door has rotated through 180 degrees. No. 6 wire (d = 0.192 inches) is used for the spring. The maximum stress developed in the spring is 150,000 psi. What is the required diameter of the torsional helical spring, the initial angular deformation of the spring and the number of active coils in the spring?