A design engineer needs to purchase a membrane module $(\mathrm{M})$ for a plant. Details about the two available options, $\text{M1}$ and $\text{M2,}$ are given in the table below. The overall plant has an expected life of $7$ years. If the interest rate is $8 \%$ per annum, compounded annually, the difference in the net present value $\text{(NPV)}$ of these two options, in lakhs of rupees, is (rounded off to one decimal place).
$$\begin{array}{|c|c|c|}
\hline & \textbf{M1} & \textbf{M2} \\
\hline \text{Purchase cost (in lakhs of rupees)}& 10 & 5 \\
\hline \text{Expected life (years)} & 5 & 3 \\
\hline
\end{array}$$