diff --git a/300s School/NUCE 2113 - Radiation Detection and Measurement/Laboratory 5.md b/300s School/NUCE 2113 - Radiation Detection and Measurement/Laboratory 5.md
index e89e220ef..11cab5386 100644
--- a/300s School/NUCE 2113 - Radiation Detection and Measurement/Laboratory 5.md	
+++ b/300s School/NUCE 2113 - Radiation Detection and Measurement/Laboratory 5.md	
@@ -12,3 +12,8 @@ We set the lower level discretization to 130. 75 still incorporated background n
 Accurate coefficients are in the cobalt ASCII file.
 
 First rip on the unknown sample, 616 counts at 658kev
+
+Exercise 5.7
+Best guess rubidium at 657.777 134 cA gross area 2507
+With Cs source now, gross area 6886
+background count gross area 81