= Solution
Use the same surrounding basement <density> inferred in <2/b/solution>, carrying its unrounded value through the arithmetic. The intrusion's <geophysical density contrast> is
$$
\Delta\rho_i=2498-2617.9458=-119.9458\ \mathrm{kg\,m^{-3}}.
$$
The <Bouguer slab> thickness needed to produce the same negative peak is therefore
$$
\boxed{h_i=\frac{-4.0\times10^{-4}}{2\pi G(-119.9458)}\simeq7952\ \mathrm m\simeq8.0\ \mathrm{km}.}
$$
The smaller absolute <geophysical density contrast> requires a thicker body. This is an approximate \b[vertical thickness] and, if the top is close to the surface as drawn in Figure 1, an approximate base depth below that top. It is not an independent estimate of the intrusion's burial depth. For an infinite slab the anomaly does not depend on top depth; a buried top would require additional geometry. Finite width and the downward-widening outline in Figure 1 make 8 km a slab-equivalent estimate rather than a uniquely determined geological depth.
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