7200 meters
Explanation:For every 300meter depth, the temperature increase by 9°C
We want to find the depth of 216 °C
let the surface temperature = 0°C
216°C greater than the surface temperature = 216°C
First we need to find the number of times we can get 9°C from 216°C
[tex]\begin{gathered} nu\text{mber of times = }\frac{216}{9} \\ nu\text{mber of times =}24 \end{gathered}[/tex]Now we multiply the number of times by the depth given:
[tex]\begin{gathered} \text{The depth of the well = 24 }\times300 \\ \text{The depth of the well = 7200 meters} \end{gathered}[/tex]Hence, the well has to be 7200 meters deep for its temperature to be 216°C greaer than the surface temperature