diff --git a/module4/challenger.ipynb b/module4/challenger.ipynb
index 2508bf65d9ea3dd904e84333525371bfb8d32682..c225255e012d0a1b4b819fcdd74f6156dd9ba44c 100644
--- a/module4/challenger.ipynb
+++ b/module4/challenger.ipynb
@@ -9,7 +9,9 @@
   },
   {
    "cell_type": "markdown",
-   "metadata": {},
+   "metadata": {
+    "hidePrompt": false
+   },
    "source": [
     "In this document we reperform some of the analysis provided in \n",
     "*Risk Analysis of the Space Shuttle: Pre-Challenger Prediction of Failure* by *Siddhartha R. Dalal, Edward B. Fowlkes, Bruce Hoadley* published in *Journal of the American Statistical Association*, Vol. 84, No. 408 (Dec., 1989), pp. 945-957 and available at http://www.jstor.org/stable/2290069. \n",
diff --git a/module4/challenger.mlx b/module4/challenger.mlx
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diff --git a/module4/challenger_matlab.pdf b/module4/challenger_matlab.pdf
new file mode 100644
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