Convergence in probability: The inverse of the simple mean












1












$begingroup$


I have a question on convergence: I have to prove that $frac{n}{U_{n}} longrightarrow 1$ in probability, where $U_{n}=sum X_{i}$, $X_{i}sim mathrm{Exp}(1)$ and because of this, $U_{n}sim mathrm{Gamma}(n,1)$.



This problem had two parts, the other part was to prove that $frac{U_{n}}{n}longrightarrow 1$ in probability which I proved invoking the weak law for big numbers. But this, I have no clue how to prove it.



Thanks so much for your help! :)










share|cite|improve this question











$endgroup$

















    1












    $begingroup$


    I have a question on convergence: I have to prove that $frac{n}{U_{n}} longrightarrow 1$ in probability, where $U_{n}=sum X_{i}$, $X_{i}sim mathrm{Exp}(1)$ and because of this, $U_{n}sim mathrm{Gamma}(n,1)$.



    This problem had two parts, the other part was to prove that $frac{U_{n}}{n}longrightarrow 1$ in probability which I proved invoking the weak law for big numbers. But this, I have no clue how to prove it.



    Thanks so much for your help! :)










    share|cite|improve this question











    $endgroup$















      1












      1








      1





      $begingroup$


      I have a question on convergence: I have to prove that $frac{n}{U_{n}} longrightarrow 1$ in probability, where $U_{n}=sum X_{i}$, $X_{i}sim mathrm{Exp}(1)$ and because of this, $U_{n}sim mathrm{Gamma}(n,1)$.



      This problem had two parts, the other part was to prove that $frac{U_{n}}{n}longrightarrow 1$ in probability which I proved invoking the weak law for big numbers. But this, I have no clue how to prove it.



      Thanks so much for your help! :)










      share|cite|improve this question











      $endgroup$




      I have a question on convergence: I have to prove that $frac{n}{U_{n}} longrightarrow 1$ in probability, where $U_{n}=sum X_{i}$, $X_{i}sim mathrm{Exp}(1)$ and because of this, $U_{n}sim mathrm{Gamma}(n,1)$.



      This problem had two parts, the other part was to prove that $frac{U_{n}}{n}longrightarrow 1$ in probability which I proved invoking the weak law for big numbers. But this, I have no clue how to prove it.



      Thanks so much for your help! :)







      probability-theory statistics convergence exponential-distribution gamma-distribution






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Nov 29 '18 at 9:56









      Davide Giraudo

      126k16150261




      126k16150261










      asked Nov 28 '18 at 21:25









      DadadaveDadadave

      9118




      9118






















          1 Answer
          1






          active

          oldest

          votes


















          2












          $begingroup$

          I think you can use the continuous mapping theorem on the other part of the question.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            So I just have to use $g(x)=x^{-1}$, and then, since $frac{U_{n}}{n}$ converges in probability to 1, then $g( frac{U_{n}}{n})= frac{n}{U_{n}}$ converges in probability to $g(1)=1$ ? That simple? Thanks! :)
            $endgroup$
            – Dadadave
            Nov 28 '18 at 22:11






          • 1




            $begingroup$
            Yes. Ideally, you define $g(0)=0$ and note that the set of discontinuity points is indeed a $P_X$-zero-set :) (as $U_n$ can be $0$)
            $endgroup$
            – Stockfish
            Nov 29 '18 at 10:09











          Your Answer





          StackExchange.ifUsing("editor", function () {
          return StackExchange.using("mathjaxEditing", function () {
          StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
          StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
          });
          });
          }, "mathjax-editing");

          StackExchange.ready(function() {
          var channelOptions = {
          tags: "".split(" "),
          id: "69"
          };
          initTagRenderer("".split(" "), "".split(" "), channelOptions);

          StackExchange.using("externalEditor", function() {
          // Have to fire editor after snippets, if snippets enabled
          if (StackExchange.settings.snippets.snippetsEnabled) {
          StackExchange.using("snippets", function() {
          createEditor();
          });
          }
          else {
          createEditor();
          }
          });

          function createEditor() {
          StackExchange.prepareEditor({
          heartbeatType: 'answer',
          autoActivateHeartbeat: false,
          convertImagesToLinks: true,
          noModals: true,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: 10,
          bindNavPrevention: true,
          postfix: "",
          imageUploader: {
          brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
          contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
          allowUrls: true
          },
          noCode: true, onDemand: true,
          discardSelector: ".discard-answer"
          ,immediatelyShowMarkdownHelp:true
          });


          }
          });














          draft saved

          draft discarded


















          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3017736%2fconvergence-in-probability-the-inverse-of-the-simple-mean%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown

























          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          2












          $begingroup$

          I think you can use the continuous mapping theorem on the other part of the question.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            So I just have to use $g(x)=x^{-1}$, and then, since $frac{U_{n}}{n}$ converges in probability to 1, then $g( frac{U_{n}}{n})= frac{n}{U_{n}}$ converges in probability to $g(1)=1$ ? That simple? Thanks! :)
            $endgroup$
            – Dadadave
            Nov 28 '18 at 22:11






          • 1




            $begingroup$
            Yes. Ideally, you define $g(0)=0$ and note that the set of discontinuity points is indeed a $P_X$-zero-set :) (as $U_n$ can be $0$)
            $endgroup$
            – Stockfish
            Nov 29 '18 at 10:09
















          2












          $begingroup$

          I think you can use the continuous mapping theorem on the other part of the question.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            So I just have to use $g(x)=x^{-1}$, and then, since $frac{U_{n}}{n}$ converges in probability to 1, then $g( frac{U_{n}}{n})= frac{n}{U_{n}}$ converges in probability to $g(1)=1$ ? That simple? Thanks! :)
            $endgroup$
            – Dadadave
            Nov 28 '18 at 22:11






          • 1




            $begingroup$
            Yes. Ideally, you define $g(0)=0$ and note that the set of discontinuity points is indeed a $P_X$-zero-set :) (as $U_n$ can be $0$)
            $endgroup$
            – Stockfish
            Nov 29 '18 at 10:09














          2












          2








          2





          $begingroup$

          I think you can use the continuous mapping theorem on the other part of the question.






          share|cite|improve this answer









          $endgroup$



          I think you can use the continuous mapping theorem on the other part of the question.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 28 '18 at 21:42









          angryavianangryavian

          40.7k23380




          40.7k23380












          • $begingroup$
            So I just have to use $g(x)=x^{-1}$, and then, since $frac{U_{n}}{n}$ converges in probability to 1, then $g( frac{U_{n}}{n})= frac{n}{U_{n}}$ converges in probability to $g(1)=1$ ? That simple? Thanks! :)
            $endgroup$
            – Dadadave
            Nov 28 '18 at 22:11






          • 1




            $begingroup$
            Yes. Ideally, you define $g(0)=0$ and note that the set of discontinuity points is indeed a $P_X$-zero-set :) (as $U_n$ can be $0$)
            $endgroup$
            – Stockfish
            Nov 29 '18 at 10:09


















          • $begingroup$
            So I just have to use $g(x)=x^{-1}$, and then, since $frac{U_{n}}{n}$ converges in probability to 1, then $g( frac{U_{n}}{n})= frac{n}{U_{n}}$ converges in probability to $g(1)=1$ ? That simple? Thanks! :)
            $endgroup$
            – Dadadave
            Nov 28 '18 at 22:11






          • 1




            $begingroup$
            Yes. Ideally, you define $g(0)=0$ and note that the set of discontinuity points is indeed a $P_X$-zero-set :) (as $U_n$ can be $0$)
            $endgroup$
            – Stockfish
            Nov 29 '18 at 10:09
















          $begingroup$
          So I just have to use $g(x)=x^{-1}$, and then, since $frac{U_{n}}{n}$ converges in probability to 1, then $g( frac{U_{n}}{n})= frac{n}{U_{n}}$ converges in probability to $g(1)=1$ ? That simple? Thanks! :)
          $endgroup$
          – Dadadave
          Nov 28 '18 at 22:11




          $begingroup$
          So I just have to use $g(x)=x^{-1}$, and then, since $frac{U_{n}}{n}$ converges in probability to 1, then $g( frac{U_{n}}{n})= frac{n}{U_{n}}$ converges in probability to $g(1)=1$ ? That simple? Thanks! :)
          $endgroup$
          – Dadadave
          Nov 28 '18 at 22:11




          1




          1




          $begingroup$
          Yes. Ideally, you define $g(0)=0$ and note that the set of discontinuity points is indeed a $P_X$-zero-set :) (as $U_n$ can be $0$)
          $endgroup$
          – Stockfish
          Nov 29 '18 at 10:09




          $begingroup$
          Yes. Ideally, you define $g(0)=0$ and note that the set of discontinuity points is indeed a $P_X$-zero-set :) (as $U_n$ can be $0$)
          $endgroup$
          – Stockfish
          Nov 29 '18 at 10:09


















          draft saved

          draft discarded




















































          Thanks for contributing an answer to Mathematics Stack Exchange!


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          Use MathJax to format equations. MathJax reference.


          To learn more, see our tips on writing great answers.




          draft saved


          draft discarded














          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3017736%2fconvergence-in-probability-the-inverse-of-the-simple-mean%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown





















































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown

































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown







          Popular posts from this blog

          Biblatex bibliography style without URLs when DOI exists (in Overleaf with Zotero bibliography)

          ComboBox Display Member on multiple fields

          Is it possible to collect Nectar points via Trainline?