Question

A Mercury in glass thermometer reads -200C at the ice point and 1000C at the steam point, Calculate the Celcius Temperature corresponding to 70° on the thermometer

Answer 1

Find how the temperature in the strange thermometer depends on the normal Celsius scale. Assume x is Celsius scale and y is strange scale:

$$y-y_1=m(x-x_1),\\ y-(-200)=m(x-0),\\ m=\frac{1000-(-200)}{100-0}=12.\\\space\\ y=12x-200.$$

So, 70°C will be

$$y=12·70-200=4C$$

on the strange thermometer.