Display the printed output produced by executing the following SAS program. Show what is in the program data vector at the point the first observation is to be written to the SAS data set.

data b21;

input Y1 Y2 @@;

Y3=Y2**2-5.0;

Y4=sqrt(Y1)/2+1;

drop Y1 Y2;

datalines;

4 -3 0 2 9 . 16 5 1 12

;

proc print data=b21;

run;