Equal spacing with enumerate and multicol

Question

I want to create a worksheet that gives equal vertical spacing for all problems. I have two questions.

• What can I do to interchange parts (b) and (c) so that parts (a) and (b) are on the same line and parts (c) and (d) are on the same line? (This was asked in a previous problem. I'm wondering if there is an easier solution, though.)

• Once this interchanging is finished, how can I alter the code so that parts (a) and (b) of problem 1, parts (c) and (d) of problem 1, and problem 2 all have equal amounts of vertical spacing? (These three spaces should take up the entire page.)

  \documentclass[10pt]{article}
  
  \usepackage{enumitem}
  \usepackage{multicol}
  \usepackage[margin=1.0in]{geometry}
  
  \begin{document}
  
  \begin{enumerate}
  % Problem 1
  \item First problem directions go here.
  \begin{multicols}{2}
  \begin{enumerate}
  \item This is part (a).
  \item This is part (b).
  \item This is part (c).
  \item This is part (d).
  \end{enumerate}
  \end{multicols}
  \vspace*{\stretch{1}}
  % Problem 2
  \item Second problem goes here.
  \vspace*{\stretch{1}}
  \end{enumerate}
  
  \end{document}
  

Answer 1

Here is an elementary implementation using minipages:

\documentclass{article}
\usepackage[margin=1in]{geometry}% http://ctan.org/pkg/geometry
\newlength{\subproblemhang}
\newcommand{\subproblem}[3][.5\linewidth]{%
  \settowidth{\subproblemhang}{(#2)~}%
  \begin{minipage}[t]{#1}
    \hangindent=\subproblemhang\hangafter=1%
    (#2)~#3
  \end{minipage}%
}

\begin{document}

\begin{enumerate}
% Problem 1
\item First problem directions go here. \par
\subproblem{a}{This is part (a).}%
\subproblem{b}{This is part (b).}

\vfill

\subproblem{c}{This is part (c).}%
\subproblem{d}{This is part (d).}

\vfill

% Problem 2
\item Second problem goes here.

\vfill

\end{enumerate}

\end{document}

This requires manual specification of the "sub problem" numbering, but this can also be changed, if needed. It depends on how far one is willing to automate things. \subproblem[<width>]{<number>}{<stuff>} allows you to specify the <number> of the problem <stuff>, including an optional <width> (default is 0.5\linewidth for a 2-column look) if you wish to have more than two "columns". Equal spacing between elements is provided by \vfill.

If you use greater-than-one-line "sub problem" statements, then the spacing will be different. However, then one can use a fixed minipage height to adjust each "sub problem" correctly. For now though, this might be sufficient.