Variance exercises

source/sec-Expected-Value.ptx

@@ -624,14 +624,14 @@
       <p>
         A continuous random variable <m>X</m> taking values in <m>[1, 4]</m> has p.d.f.
         <m>f(x) = k(x - \sqrt{x})</m> for some constant <m>k</m>.
-        In a previous problem, you found the value of <m>k</m>.
+        In a previous problem (<xref ref="exercise-continuous-RV-find-k"/>), you found the value of <m>k</m>.
         Now, find <m>\E(X)</m>.
       </p>
     </statement>
 
     <answer>
       <p>
-        <m>E(X) \approx 3.04.</m>
+        <m>\frac{258}{85} \approx 3.04.</m>
       </p>
     </answer>
   </exercise>
@@ -647,7 +647,7 @@
 
     <answer>
       <p>
-        <m>\frac{1}{2}\left( \ln(2) + \frac{7}{3}\right) \approx 1.513.</m>
+        <m>\frac{1}{2}\left( \ln(2) + \frac{7}{3}\right) \approx 1.513</m>.
       </p>
     </answer>
   </exercise>