$\backslash$table$[[$Depth$,z(m)$:$,0,0\mathrm{.}5,1\mathrm{.}0,1\mathrm{.}5,2\mathrm{.}0,2\mathrm{.}5,3\mathrm{.}0],[$Temperature $(0),70,68,55,22,13,11,10]]$

Problem $1($Regression$/$Curve fitting$)$: The point at Which the temp. $-$ depth Curve has Zero Curvature $($i$.$e$.)\frac{d^{2}r}{d{z}^2}{|}_z||=0=0$ is Called the thermocline. Fit a Cubic polynomial for this $($entire$)$ dataset and using the same Solve for $z_0($the thermocline depth$)$

Please solve by handwritten method.