Below Is a Partial Multiple Regression Computer Output Based on a Quadratic

Below is a partial multiple regression computer output based on a quadratic regression model.
$$\begin{array} { l l l } \text { Source } & \text { SS } & \text { df } \\\text { Model } & 29.44 & 2 \\\text { Error } & 59.96 & 15 \\\\& & \text { Standard Error } \\\text { Variable } & \text { Coefficient } & \left( \mathrm { s } _ { \mathrm { s } } \right) \\\text { Intercept } & 8.01 & 1.45 \\\mathrm { X } & - 1.35 & 0.55 \\\mathrm { X } ^ { 2 } & 0.46 & 0.43\end{array}$$
-Determine the number of observations in the sample,explained variation and the MSE.