Vibrations of a motor (40Hz) cause noise on the signal of a strain gauge that monitors load on a cantilever that measures periodic load changes at the rate of 1/minute. Design a filter that reduces the signal caused by the vibrations by 90%. I thought about a low pass filter that has a cut off frequency of 40Hz but I'm not sure about the reduction by 90% bit. Is there an equation linking frequency to the gain of a circuit because a 90% reduction would be -20dB according to gain=20log(Vout/Vin) or -10dB if you used gain=10log(Pout/Pin). I am unsure how to do this and any help would be greatly appreciated.