\documentclass[12pt,letterpaper]{article}
\usepackage{epsfig,graphics,rotating}
\setlength{\oddsidemargin}{-0.2in}
\setlength{\evensidemargin}{-0.2in}
\setlength{\topmargin}{0.in}
\setlength{\headheight}{0in}
\setlength{\footskip}{0.3in}
\setlength{\headsep}{0.1in}
\setlength{\textheight}{24cm}
\setlength{\textwidth}{18cm}
%\setlength{\parindent}{0in}
\setlength{\marginparsep}{0in}
\setlength{\marginparwidth}{0in}
\pagestyle{empty}
%\usepackage{multicol}
\def\gs{\mathrel{\raise1.16pt\hbox{$>$}\kern-7.0pt
\lower3.06pt\hbox{{$\scriptstyle \sim$}}}}
\def\ls{\mathrel{\raise1.16pt\hbox{$<$}\kern-7.0pt
\lower3.06pt\hbox{{$\scriptstyle \sim$}}}}

\begin{document}

\begin{center}
{\bf \Large Distribuci\'on binomial}
\end{center}


\[
\bf
P(n)= \frac{N!}{n!(N-n)!}p^Nq^{N-n}
\]

\vspace{0.5cm}
\begin{center}
\resizebox{\textwidth}{!}{\rotatebox{-90}{\epsfig{file=binom_20_0.5.ps}}} 
\end{center}

\begin{center}
\resizebox{\textwidth}{!}{\rotatebox{-90}{\epsfig{file=binom_20_0.7.ps}}} 
\end{center}

\newpage

\[ \bf
P(n)= \frac{N!}{n!(N-n)!}p^Nq^{N-n}
\]
\[
\bf
P(n) \sim \frac{1}{\sqrt{2\pi N p q}} e^{-\frac{(n-Np)^2}{2Npq}}
\]

\vspace{0.5cm}
\begin{center}
\resizebox{\textwidth}{!}{\rotatebox{-90}{\epsfig{file=binom_20_0.7_g.ps}}} 
\end{center}

\begin{center}
\resizebox{\textwidth}{!}{\rotatebox{-90}{\epsfig{file=binom_100_0.7_g.ps}}} 
\end{center}

\end{document}