In assignment $2,$ we predict Purchase with all the other variables as predictors using the data OJ$.$csv$.$ One tree model TreeOJ and one Random forest model RFOJ have been developed respectively to fit this data set and their prediction performance have been evaluated. The following paragraph shows partial outputs from the two models: Answer the following two questions based on the above paragraph of outputs. Please enter your answers in the box after each question. $1)$ Based on the ten$-$fold cross$-$validation error rate, what is the optimal size of TreeOJ?$2)$ What is the overall prediction accuracy of RFOJ? Show your answer as a number to three decimal places, e$.$g$.,0\mathrm{.}000.$ Rounding if necessary.