Here is the block diagram for a feedback control system.

The Bode' plot below is for G(s).

• The information above is all you know about the system.
• You don't know the transfer function.
• You don't know anything else about the system - even what it is.
• Determine the gain which will produce a phase margin of 30^o.
• Determine the gain which will produce a phase margin of 40^o.