\documentclass{article}
\usepackage[active,tightpage]{preview}
\usepackage{varwidth}
\usepackage{pgfplots}
\begin{document}
\begin{preview}
\begin{varwidth}{\linewidth}
\centering
\tikzset{every mark/.append style={scale=4}}
\begin{tikzpicture}
\begin{axis}[title=Case C (raw data),
	height=8cm, 
	width=8cm,		
 	legend pos=south east, 
 	xlabel={Horizontal Axis ($1^{st}$ feature)},
    	ylabel={Vertical Axis ($2^{nd}$ feature)},
]
%marcadores = página 159 da documentação do pgf plots
\addplot[
scatter,
only marks,
point meta=explicit symbolic,
scatter/classes={
c1={mark size=1,mark=triangle*,fill=blue},%
c2={mark size=1,mark=square*,fill=red}},
]
table[meta=label] {./caso5.txt};
\legend{Class 1, Class 2}

\end{axis}
\end{tikzpicture}
\pgfmathdeclarefunction{gauss}{2}{%
  \pgfmathparse{1/(#2*sqrt(2*pi))*exp(-((x-#1)^2)/(2*#2^2))}%
}

\begin{tikzpicture}
\begin{axis}[title=Horizontal Axis distribution, width=6.5cm,height=3.5cm,ymax=1,
every axis plot post/.append style={
  mark=none,domain=-5:10,samples=50,smooth}, % All plots: from -2:2, 50 samples, smooth, no marks
  axis x line*=bottom, % no box around the plot, only x and y axis
  axis y line*=left, % the * suppresses the arrow tips
  enlargelimits=upper] % extend the axes a bit to the right and top
  \addplot {gauss( 4.0898 ,0.3992)};
  \addplot {gauss(4.6557 ,2.4367)};
\end{axis}
\end{tikzpicture}
\begin{tikzpicture}
\begin{axis}[title=Vertical Axis distribution, width=6.5cm,height=3.5cm,ymax=1,
every axis plot post/.append style={
  mark=none,domain=-5:10,samples=50,smooth}, % All plots: from -2:2, 50 samples, smooth, no marks
  axis x line*=bottom, % no box around the plot, only x and y axis
  axis y line*=left, % the * suppresses the arrow tips
  enlargelimits=upper] % extend the axes a bit to the right and top
  \addplot {gauss(0.0060	, 2.3823)};
  \addplot {gauss(6.0017,0.9089)};
\end{axis}
\end{tikzpicture}

\end{varwidth}
\end{preview}
\end{document}