PROC IMPORT OUT= WORK.raw 
            DATAFILE= "C:\Teaching\STAT481\FuelAdditive.xls"
            DBMS=EXCEL REPLACE;
	    sheet="sheet1";
            GETNAMES=yes;
RUN;

proc print data=raw;
run;

data additive;
set raw;
Ratio=Control/Test;
run;

proc sort data=additive;
by Laps;
run;

/* Normality Check*/
   title 'Normality Check';
   proc univariate data=additive normal;
   by Laps;
   var Ratio;
   QQPlot / Normal(mu=est sigma=est);
   run;

title '2-sample t-test';
     proc ttest data=additive;
      class Laps;
      var Ratio;
   run;