fix math rendering issue

Author: Benjamin T. Vincent

examples/case_studies/binning.ipynb

@@ -2724,20 +2724,20 @@
     "We will now empirically verify that the parameters of other distributions are recoverable using the same methods. We will approximate the distribution of [Body Mass Index](https://en.wikipedia.org/wiki/Body_mass_index) (BMI) from 2 hypothetical (simulated) studies. \n",
     "\n",
     "In the first study, the fictional researchers used a set of thresholds which give them many categories of:\n",
-    "- Underweight (Severe thinness): $<16$\n",
-    "- Underweight (Moderate thinness): $16–17$\n",
-    "- Underweight (Mild thinness): $17–18.5$\n",
-    "- Normal range: $18.5–25$\n",
-    "- Overweight (Pre-obese): $25–30$\n",
-    "- Obese (Class I): $30–35$\n",
-    "- Obese (Class II): $35–40$\n",
-    "- Obese (Class III): $\\ge40$\n",
+    "- Underweight (Severe thinness): $< 16$\n",
+    "- Underweight (Moderate thinness): $16 - 17$\n",
+    "- Underweight (Mild thinness): $17 - 18.5$\n",
+    "- Normal range: $18.5 - 25$\n",
+    "- Overweight (Pre-obese): $25 - 30$\n",
+    "- Obese (Class I): $30 - 35$\n",
+    "- Obese (Class II): $35 - 40$\n",
+    "- Obese (Class III): $\\ge 40$\n",
     "\n",
     "The second set of researchers used a categorisation scheme recommended by the Hospital Authority of Hong Kong:\n",
     "- Underweight (Unhealthy): $< 18.5$\n",
-    "- Normal range (Healthy): $18.5–23$\n",
-    "- Overweight I (At risk): $23–25$\n",
-    "- Overweight II (Moderately obese): $25–30$\n",
+    "- Normal range (Healthy): $18.5 - 23$\n",
+    "- Overweight I (At risk): $23 - 25$\n",
+    "- Overweight II (Moderately obese): $25 - 30$\n",
     "- Overweight III (Severely obese): $\\ge 30$"
    ]
   },