Four different thermometers were used to measure the temperature of a sample of impure boiling water. The measurements are recorded in the table below. Thermometer Temperature
Reading 1 Temperature
Reading 2 Temperature
Reading 3
W 100.1°C 99.9°C 96.9°C
X 100.4°C 102.3°C 101.4°C
Y 90.0°C 95.2°C 98.6°C
Z 90.8°C 90.6°C 90.7°C

The actual boiling point of pure water is 100.0°C.

What can be concluded from the data about the reliability and validity of the thermometers?