I'm stuck on a problem trying to determine charge, and I'm hoping someone can help. Suppose that a = 5.00 cm, b = 20.0 cm, and c = 25.0 cm. Furthermore, suppose that the electric field at a point 15.5 cm from the center is measured to be 3.70 *103 N/C radially inward while the electric field at a point 50.0 cm from the center is 2.50 *102 N/C radially outward. http://www.webassign.net/pse/p24-57.gif From this information, find the following charges. (Include the sign of the charges.) (a) the charge on the insulating sphere At first i worked out the whole EA=Q/Epsilon(0); and tried 4pi(r^2)*Epsilon*3.7e3 in order to solve for Q, but it didnt work out; what am I doing wrong?