Alignment issues due to vspace and hfill

Question

Facing issues with alignment (the 3 and 4 are out of alignment), I suspect it has to do with the vspace and hfill issue. Please assist.

\begin{enumerate}[\textbf{(\roman*)}]
\item Using a scale of 1 cm to 0.1 unit on each axis, plot $\lg y$ against $\lg x$ and draw a straight line graph. \hfill [3]
\item Use your graph to estimate the value of $k$ and of $n$. \hfill [4]
\vspace{\baselineskip}\newline\vspace{0.000001cm} \hfill [$k=84.2$, $n=1.35$]
\end{enumerate}

Answer 1

Simply adding a blank line instead of applying a \vspace will resolve the issue:

Code:

\documentclass{article}
\begin{document}
\begin{enumerate}
\item Using a scale of 1 cm to 0.1 unit on each axis, plot $\lg y$ against $\lg x$ and draw a straight line graph. \hfill [3]
\item Use your graph to estimate the value of $k$ and of $n$. \hfill [4]
\hfill [$k=84.2$, $n=1.35$]
\end{enumerate}
\end{document}

Answer 2

this looks like a situation where \\ (after the [4]) is actually justifiable:

\item Use your graph to estimate the value of $k$ and of $n$. \hfill [4]\\
\hfill [$k=84.2$, $n=1.35$]