diff --git a/is/ub7/is7.pdf b/is/ub7/is7.pdf
index c2f1820..2d8ad27 100644
--- a/is/ub7/is7.pdf
+++ b/is/ub7/is7.pdf
Binary files differ
diff --git a/is/ub7/is7.tex b/is/ub7/is7.tex
index 81f9e0b..4a94703 100644
--- a/is/ub7/is7.tex
+++ b/is/ub7/is7.tex
@@ -100,8 +100,12 @@
     \Aufgabe{Causal effects}{60}
         \begin{enumerate}[(a)]
             \item see above
-            \item Setting $\alpha$ to $0$ makes Z independent of X.\\
-                Z is just random noise ($N_z$), so it is independent of X\qed
+            \item %Setting $\alpha$ to $0$ makes Z independent of X.\\
+                %Z is just random noise ($N_z$), so it is independent of X\qed
+                % aber es ist doch gefragt wann W unabhängig von X ist
+                 $W=-4V-0.5X+0.5N_y+2\alpha X+2N_z+N_w$\\
+	                for $\alpha =0.25$\\
+	               $W=-4V+0.5N_y+2N_z+N_w$ 
             \item \begin{align*}
                 \frac{d}{dx}\mathds{E}\left(W|do\ X=x\right)&=-4\frac{d\mathds{E}(V|do\ X=x)}{dx}+0.5\frac{d\mathds{E}(Y|do\ X=x)}{dx}+2\frac{d\mathds{E}(Z|do\ X=x)}{dx}\\
                 &=0.5\cdot\left(-1\right)+2\cdot\alpha\\