\begin{Schunk}
\begin{Sinput}
 par(mfcol=c(2,2))
 hist(dat2$x1, main = "Normal", prob = TRUE, breaks = 20,  xlab = paste("E[x] = 4"), xlim = c(-16,24))
 hist(dat2$x2, main = "Poisson", prob = TRUE, breaks = 20, xlab = paste("E[x] = 4"), xlim = c(-16,24))
 hist(dat2$x3, main = "Gamma", prob = TRUE, breaks = 20, xlab = paste("E[x] = 4"), xlim = c(-16,24))
 hist(dat2$x4, main = "Binomial", prob = TRUE, breaks = 20, xlab = paste("E[x] = 4"), xlim = c(-16,24))
\end{Sinput}
\end{Schunk}
