In the determination of Young's modulus $\left(Y=\frac{4 \mathrm{MLg}}{\pi \mathrm{ld}^2}\right)$ by using Searle's method, a wire of length $\mathrm{L}=2 \mathrm{~m}$ and diameter $\mathrm{d}=0.5 \mathrm{~mm}$ is used. For a load $\mathrm{M}=2.5 \mathrm{~kg}$, an extension $\ell=0.25 \mathrm{~mm}$ in the length of the wire is observed. Quantities d and $\ell$ are measured using a screw gauge and a micrometer, respectively. They have the same pitch of 0.5 mm . The number of divisions on their circular scale is 100 . The contributions to the maximum probable error of the Y measurement