Question

Calculate Open Circuit Voltage of the Voltage Source
Using minimum number of components design a voltage divider which can deliver 1 W at 100 V, 2 W at -50 V and 1.6 W at -80 V. The voltage source has an internal resistance of 200 ohms and supplies a current of 100 mA. What is the open circuit voltage of the voltage source?

Answer 1

See the  diagrams enclosed.

Perhaps the open circuit voltage of the source is around 120 V  found from using the graph using linear interpolation.  If curved interpolation is used, perhaps around 108V..  Perhaps there is a better way to find the answer.