% This file is public domain
\documentclass[a4paper]{report}

\usepackage{probsoln}

\begin{document}
\hideanswers

\chapter{Easy Problems}
\loadrandomproblems[easyproblems]{5}{prob-easy2}

\renewcommand{\theenumi}{\thechapter.\arabic{enumi}}
\begin{enumerate}
\foreachproblem[easyproblems]{\item\label{prob:\thisproblemlabel}\thisproblem}
\end{enumerate}

\chapter{Probability Spaces}
\loadrandomproblems[probspaces]{2}{prob-probspaces2}

\renewcommand{\theenumi}{\thechapter.\arabic{enumi}}
\begin{enumerate}
\foreachproblem[probspaces]{\item\label{prob:\thisproblemlabel}\thisproblem}
\end{enumerate}

\appendix
\chapter{Solutions}
\showanswers
\begin{enumerate}
\foreachdataset{\thisdataset}{%
\foreachproblem[\thisdataset]{\item[\ref{prob:\thisproblemlabel}]\thisproblem}
}
\end{enumerate}

\end{document}