$$ \begin{array}{1} \text { Data: }\\ \begin{array}{rrrr} & \text { X1 } & \text { X2} &\text { X3} \hline 0 & 1 & 4 & \text { a } 1 & 1 & 3 & \text { b } 2 & 3 & 4 & \text { a } 3 & 5 & 1 & \text {c} W 4 & 6 & 3 & \text { b } 5 & 4 & 0& \text { b } \end{array} \end{array} $$ CS.VS. 1115