Create a new variable EEG$\_3$D and assign to it a matrix of NaNs with $5$ rows, $100$ columns, and $6$pages$($third dimension$).$ Assign the values of the first and fourth pages of EEG$\_3$D with the first $5$ channels, from time points $1$ to $100.$ Assign the values of the second and fifth pages of EEG$\_3$D with channels $6$ to $10,$ from time points $101$ to $200.$ Assign the third and sixth pages of EEG$\_3$D with a value of $23.$

Output the values of EEG$\_3$D$(3,42,$:$).$

Create a variable EEG$\_$subset that includes the time points $601$:$650$ from channel $7.$ Randomize the values in EEG$\_$subset by placing the values in new positions that are given by randperm$(50).($Hint$,$ you can do this in one line of code.$)$