A digital thermometer reads from -120 to + 300 degC. The accuracy is guaranteed to plus or minus 2% f.s.d. Determine the possible temperature range when it indicates 80 degC.
The range of the instrument is the same as the f.s.d. and is 420.
The accuracy is hence plus or minus 2% of 420.
Accuracy = (2/100)(420) = 8.4
The possible temperature being indicated is hence 80 plus or minus 8.4.
That means the actual temperature is between 88.4 and 71.6 degC.