An averaging amplifier has five inputs. The ratio Rf>Rin must be

The ratio Rf/Rin for an averaging amplifier with five inputs should be 4. This is because the output voltage of an averaging amplifier is the average of the input voltages. The ratio Rf/Rin determines the gain of the amplifier. For an averaging amplifier, the gain is 1/n, where n is the number of inputs. Therefore, for five inputs, the gain is 1/5. However, in practical applications, to account for losses in the amplifier, the ratio Rf/Rin is often set slightly higher than 1/n. Therefore, for an averaging amplifier with five inputs, a good choice for the ratio Rf/Rin would be slightly higher than 1/5, but for ideal conditions, it should be 4.