option linesize =72 nodate;
data travel;
input x n y;
w = sqrt(n);
datalines;
27	2	37.5
36	2	47.5	
26	2	40.0
31	2	30.0
35	2	40.0
35	2	45.0
31	2	37.5
36	2	42.5
;
run;
proc reg;
model y=x;
weight w;
run;
proc reg;
model y=x;
run;