In order to calculate the heat loss through the wall of a building, it is necessary to know the temperature difference between the inside and outside walls. If temper-atures of 5°C and 20°C are measured on each side of the wall by mercury-in-glass thermometers with a range of 0°Cto 50°C and a quoted inaccuracy figure of +-1% of full-scale reading, calculate the likely maximum possible error in the calculated figure for the temperature difference.