Number of background "under" a signal


Is there a certain way to return the number of background events within a signal region–or a specified region for that matter?

i.e. (paraphrased version)

RooAbsPdf *pdfX = new RooVoigtian("pdfX", "pdfX", Mass_Range_X, X_peak, X_width,X_resSigma);

RooAbsPdf  *BkgPolPdf  = new RooChebychev("bkg","background", Mass_Range_X, RooArgList(*bkg_a1,*bkg_a2, *bkg_a3));

RooExtendPdf *  expdfX = new RooExtendPdf("extendpdfSigX","Signal X PDF",*pdfX, nSigX);
	RooExtendPdf *  exBkgPolPdf = new RooExtendPdf("exBkgPolPdf","Signal 1 PDF",*BkgPolPdf, nBckPol);

RooAddPdf *mytotalPdf= new RooAddPdf("mytotPdf", "mytotPdf", RooArgList( *expdfX,*exBkgPolPdf) ) ;

Now say my signal is in a range [a,b], how could I only return the number of background events in this range = "the background “under the signal”.

Sorry if this is just a small deviation from a large amount of other posts.[/code]

Nevermind, I found a tutorial that covers it =D