You may wish to refer to a brief discussion of the Wheatstone bridge.
A motor with an eccentric load is turning at 1200 rpm. A strain gauge is used to monitor the vibration in the motor mounting. The Wheatstone bridge and amplifier produce an output voltage proportional to the strain in the mounting. The capacitor blocks the dc component from the bridge, ac-coupling the amplifier.
HINT: Find the Thévenin equivalent for the Wheatstone bridge!
This problem is from Roadstrum and Wolaver Ch. 8, Problem 9.