4A common misconception for people learning to apply the slope-intercept formula to linear instrument ranges is that they tend to assume b will always be equal to the lower-range value (LRV) of the instrument’s output range. For example, given a transmitter with a 4-20 mA output range, the false assumption is that b = 4. This does happen to be true only if the instrument possesses a “dead-zero” input range, but it will not be true for instruments with a live-zero input range such in this case here where the temperature input range is 50 to 140 degrees.