b
\(M \cdot S \cdot \quad 20 d i v=1 \mathrm{cm}\)

\(1 \mathrm{MsD}=\frac{1}{20} \mathrm{cm}=0.05 \mathrm{cm}\)

\(10 \mathrm{VsD}=9 \mathrm{MsD}\)

\(\mid V S  D=\frac{9}{10} \times M S D=\frac{9}{10} \times 0.05 \mathrm{cm}\)

\(L \cdot c=1 \mathrm{MsD} -1 \mathrm{VsD}\)

\(=0.05-\frac{9}{10} \times 0.05=\frac{1}{10} \times 0.05\)

\(L c=0.005 \mathrm{cm}\)

zero error: \(=6 \times L C=6 \times 0.005\)

Zero error \(=0.03 \mathrm{cm}\)

Reading \(=\mathrm{M} \cdot \mathrm{sD}+\mathrm{VsD}\)

\(=3 \cdot 2+8 \times L \cdot c\)

\(=3 \cdot 2+8 \times 0.005\)

\(=3 \cdot 2+0.04=3.24 \mathrm{cm}\)

Actual reading = Reading - zero emor

\(=3 \cdot 2 4-0.03=3 \cdot 21 \mathrm{cm}\)

Reading \(=\operatorname{MsR}+V S R\)

\(=1.5+6 \times 10\)

\(=1.5+6 \times 0.005=1.53\)

\(=1.5+0.03=1.53\)

A ctual reading = Reading - zero error

\(=1.530-0.03=1.5 \mathrm{cm}\)