$\begin{aligned}
& 1 \mathrm{MSD}=\frac{1 \mathrm{cm}}{20}=0.05 \mathrm{cm} \
& 1 \mathrm{VSD}=\frac{49}{50} \mathrm{MSD}=\frac{49}{50} \times 0.05 \mathrm{cm}=0.049 \mathrm{cm} \
& \mathrm{LC}=1 \mathrm{MSD}-1 \mathrm{VSD}=0.001 \mathrm{~cm}
\end{aligned}$
For mark on paper, L1=8.45 cm+26×0.001 cm =84.76 mm For mark on paper through slab, L2=7.12 cm+ 41×0.001 cm=71.61 mm For powder particle on top surface, ZE=4.05 cm +1×0.001 cm=40.51 mm
∴⇒ actual L1=84.76−40.51=44.25 mm actual L2=71.61−40.51=31.10 mm L2=μL1μ= L2L1=31.1044.25=1.42