b$.$ Sort by$$x$1,$ then by$$x$2,$ then by$$x$3,$and then by$$x$4,$ all in ascending order. Note that all variables are sorted simultaneously. After the variables have been sorted, what is the first observation for$$x$1,$x$2,$x$3,$and$$x$4?$

Note: For$$x$1,$ round your answer to four decimal places.

HINT: Use Data $-$ Sort dialog