Update docs/3_drude_model_solutions.md

docs/3_drude_model_solutions.md

@@ -78,7 +78,7 @@ See 3_drude_model.md
     $$
     R_H = \frac{n_h\mu_h^2 - n_e\mu_e^2}{e(n_h\mu_h + n_e \mu_e)^2}
     $$
-    The sign is determined by a weighted average of the charge density and the mobilty of the positive and negative charge carriers. Therefore, a measurement of the Hall voltage reveals the dominant charge carrier
+    We observe that the sign of $R_H$ is determined by the density and the mobilty of the positive and negative charge carriers. Therefore, a measurement of the Hall voltage reveals the dominant charge carrier.
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 Solution extra exercise: