[spec] add section on circle mensuration

diff --git a/methods/statistics.tex b/methods/statistics.tex
index 3a205e575c41e43881b0fe4e00e51d62c26437a0..b25d0455e3c11f0457f2a9a7e73b4d109da7d35c 100644 (file)
--- a/methods/statistics.tex
+++ b/methods/statistics.tex
@@ -203,6 +203,6 @@
 
   \[ \operatorname{E}(X) = \int^b_a x f(x) \> dx \]
 
-  \[ \operatorname{sd}(X) = \sqrt{\operatorname{Var}(X)} = \sqrt{\oepratorname{E}(X^2)-[\operatorname{E}(X)]^2} \]
+  \[ \operatorname{sd}(X) = \sqrt{\operatorname{Var}(X)} = \sqrt{\operatorname{E}(X^2)-[\operatorname{E}(X)]^2} \]
 
 \end{document}