n_list<-c(2,5,10,30) # Ç¥º»¼ö(n)
df_list<-n_list-1 # ÀÚÀ¯µµ

curve(dt(x, 1, ncp=0), col="blue", xlim=c(-4, 4), ylim=c(0, 0.5), xlab="t", ylab="f(t)")
text(x=-1.1,y=0.1, label="df=1", cex=0.7)
curve(dt(x, 4, ncp=0), add=T, col="red", xlim=c(-4, 4), ylim=c(0, 0.5), xlab="t", ylab="f(t)")
text(x=-0.45,y=0.3, label="df=4",cex=0.7)
curve(dt(x, 9, ncp=0), add=T, col="green", xlim=c(-4, 4), ylim=c(0, 0.5), xlab="t", ylab="f(t)")
text(x=-0.45,y=0.4, label="df=9",cex=0.7)
curve(dt(x, 29, ncp=0), add=T, col="black", xlim=c(-4, 4), ylim=c(0, 0.5), xlab="t", ylab="f(t)")
text(x=0.45,y=0.41, label="df=29",cex=0.7)
arrows(0.43,0.39,0.4,0.365, length=.05)
par(mfrow=c(2,2))

for (i in 1:length(df_list)) {
  
  curve(dt(x, df_list[i], ncp=0), xlim=c(-4, 4), ylim=c(0, 0.5), xlab="t", ylab="f(t)", main=paste("df=", df_list[i]))
  
}