Merge pull request zackchase#247 from ahazrat/patch-3

correct spelling of 'concerned'

chapter01_crashcourse/probability.ipynb

@@ -405,7 +405,7 @@
     "and we can say that an element $x$ is *in* the set S, by writing $x \\in S$.\n",
     "The symbol $\\in$ is read as \"in\" and dennotes membership. \n",
     "For instance, we could truthfully say $\\mathrm{dog} \\in \\{\\mathrm{cat}, \\mathrm{dog}, \\mathrm{rabbit}\\}$.\n",
-    "When dealing with the rolls of die, we are concrned with a variable $X \\in \\{1, 2, 4, 5, 6\\}$. \n",
+    "When dealing with the rolls of die, we are concerned with a variable $X \\in \\{1, 2, 4, 5, 6\\}$. \n",
     "\n",
     "Note that there is a subtle difference between discrete random variables, like the sides of a dice, \n",
     "and continuous ones, like the weight and the height of a person. \n",