diff --git a/exam/ex.tex b/exam/ex.tex
index 0ac2c4d..80afcaf 100644
--- a/exam/ex.tex
+++ b/exam/ex.tex
@@ -285,7 +285,10 @@
       $1/2^{130}$ (soundness error).
       
 
-    \item \TODO
+    \item The soundness error after one iteration is $1/2^{130}$. To achieve
+      a $1/2^{192}$ soundness error, the protocol should be done twice to arrive
+      at a soundness error of $1/2^{260}$, which is well below the required
+      $1/2^{192}$.
 
     \item \TODO