I want to create a question with multiple correct string answers in 'exams' package in R. For example, consider simple Excel-related question. Let's say the following Excel formula is the answer to a question and can be written as a string: "=A2*A3+B2*B3". However, this is not a unique way of writing the formula as there are multiple possible ways of writing the same formula in Excel. For example, the above formula can also be written as "=B2*B3+A2*A3". In latex format, we will leave the empty cell to write the answer with the expression: ~##ANSWER1##~. How can we code this (which accepts both answers as correct) using 'exams' package? I tried to write the code as follows but it does not work.
\begin{question}
Write the correct formula.
\begin{tabular}{ |l|l|l|l|}
& A & B & C \\
1 & & & \\
2 & & & \\
3 & & & Enter formula here: \\
4 & & & ~##ANSWER1##~ \\
5 & & & \\
\end{tabular}
\end{question}
\begin{solution}
<<echo=FALSE, results=hide>>=
Answer1 <- c("=A2*A3+B2*B3")
Answer2 <- c("=B2*B3+A2*A3")
soln <- c(Answer1, Answer2)
@
\begin{answerlist}
\item \Sexpr{soln}
\end{answerlist}
\end{solution}
\exname{multiple correct string answers}
\extype{cloze}
\exsolution{\Sexpr{soln}}
\exclozetype{string}
Following Achim's suggestions, I corrected the code below:
\begin{question}
Write the correct formula.
\begin{tabular}{ |l|l|l|l|}
& A & B & C \\
1 & & & \\
2 & & & \\
3 & & & Enter formula here: \\
4 & & & ~##ANSWER1##~ \\
5 & & & \\
\end{tabular}
\end{question}
\begin{solution}
<<echo=FALSE, results=hide>>=
Answer1 <- c("=A2*A3+B2*B3")
Answer2 <- c("=B2*B3+A2*A3")
soln <- "1:SHORTANSWER:%100%=A2*A3+B2*B3~%100%=B2*B3+A2*A3"
@
\begin{answerlist}
\item \Sexpr{soln}
\end{answerlist}
\end{solution}
\exname{multiple correct string answers}
\extype{cloze}
\exsolution{\Sexpr{soln}}
\exclozetype{verbatim}