library(tigerstats)
small<-c(41,45,42,62,68,54,52,55,44,60)
large<-c(74,74,70,52,76,91,71,78,76,78,83,50,52,66,65,53,72)

ns<-length(small)
nl<-length(large)

ms<-mean(small)
ml<-mean(large)

vs<-var(small)
vl<-var(large)

ss<-sd(small)
sl<-sd(large)

ns;nl;ms;ml;vs;vl;ss;sl

sp.sq<-((ns-1)*vs+(nl-1)*vl)/(ns+nl-2)
sp<-sqrt(sp.sq)
tc<-(ms-ml)/(sp*sqrt(1/ns+1/nl))

sp.sq;sp;tc

t.test(small, large, alternative="less", var.equal=T, conf.level=0.99)

t25<-qt(0.01, df=25, lower.tail=T)
t25

par(mfrow=c(2,1))
ptGC(-3.9421,region="below",df=25, graph=T)
ptGC(-2.485107,region="below",df=25, graph=T)