Chebyshev's inequality to compute the premium income












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This is a problem 9.7 from Anderson "Introduction to probability"




A car insurance company has $2,500$ policy holders. The expected claim
paid to a policy holder during a year is $1,000$ with a standard
deviation of $900$. What premium should the company charge each policy
holder to assure that with probability $0.999$ the premium income will
cover the cost of the claims? Compute the answer with both Chebyshev's inequality
and CLT.




Assuming each claim is independent, then the aggregate claims $S = sum_{i=1}^{2500} X_i$ where $X_i$ is the annual claim size for policyholder $i$, then $$operatorname{E}[S] = 2500 * operatorname{E}[X_i] = 2500 * 1000 = 2500000,$$ and variance $$operatorname{Var}[S] = 2500 operatorname{Var}[X_i] =2500 * 900^2.$$

We want to fins s (the premium income), such that $P(Sleq s)=0.999.$ This is equivalent to $P(Sgeq s)=0.001.$ By Chebyshev's inequality
$$P(Sgeq s) = P(S-operatorname{E}[S]geq s- operatorname{E}[S])leq P(|S-operatorname{E}[S]|geq s-operatorname{E}[S])leq frac{operatorname{Var}[S]}{(s-operatorname{E}[S])^2}$$



My question is how do we get the desired equality from this inequality? Thanks










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    This is a problem 9.7 from Anderson "Introduction to probability"




    A car insurance company has $2,500$ policy holders. The expected claim
    paid to a policy holder during a year is $1,000$ with a standard
    deviation of $900$. What premium should the company charge each policy
    holder to assure that with probability $0.999$ the premium income will
    cover the cost of the claims? Compute the answer with both Chebyshev's inequality
    and CLT.




    Assuming each claim is independent, then the aggregate claims $S = sum_{i=1}^{2500} X_i$ where $X_i$ is the annual claim size for policyholder $i$, then $$operatorname{E}[S] = 2500 * operatorname{E}[X_i] = 2500 * 1000 = 2500000,$$ and variance $$operatorname{Var}[S] = 2500 operatorname{Var}[X_i] =2500 * 900^2.$$

    We want to fins s (the premium income), such that $P(Sleq s)=0.999.$ This is equivalent to $P(Sgeq s)=0.001.$ By Chebyshev's inequality
    $$P(Sgeq s) = P(S-operatorname{E}[S]geq s- operatorname{E}[S])leq P(|S-operatorname{E}[S]|geq s-operatorname{E}[S])leq frac{operatorname{Var}[S]}{(s-operatorname{E}[S])^2}$$



    My question is how do we get the desired equality from this inequality? Thanks










    share|cite|improve this question

























      0












      0








      0







      This is a problem 9.7 from Anderson "Introduction to probability"




      A car insurance company has $2,500$ policy holders. The expected claim
      paid to a policy holder during a year is $1,000$ with a standard
      deviation of $900$. What premium should the company charge each policy
      holder to assure that with probability $0.999$ the premium income will
      cover the cost of the claims? Compute the answer with both Chebyshev's inequality
      and CLT.




      Assuming each claim is independent, then the aggregate claims $S = sum_{i=1}^{2500} X_i$ where $X_i$ is the annual claim size for policyholder $i$, then $$operatorname{E}[S] = 2500 * operatorname{E}[X_i] = 2500 * 1000 = 2500000,$$ and variance $$operatorname{Var}[S] = 2500 operatorname{Var}[X_i] =2500 * 900^2.$$

      We want to fins s (the premium income), such that $P(Sleq s)=0.999.$ This is equivalent to $P(Sgeq s)=0.001.$ By Chebyshev's inequality
      $$P(Sgeq s) = P(S-operatorname{E}[S]geq s- operatorname{E}[S])leq P(|S-operatorname{E}[S]|geq s-operatorname{E}[S])leq frac{operatorname{Var}[S]}{(s-operatorname{E}[S])^2}$$



      My question is how do we get the desired equality from this inequality? Thanks










      share|cite|improve this question













      This is a problem 9.7 from Anderson "Introduction to probability"




      A car insurance company has $2,500$ policy holders. The expected claim
      paid to a policy holder during a year is $1,000$ with a standard
      deviation of $900$. What premium should the company charge each policy
      holder to assure that with probability $0.999$ the premium income will
      cover the cost of the claims? Compute the answer with both Chebyshev's inequality
      and CLT.




      Assuming each claim is independent, then the aggregate claims $S = sum_{i=1}^{2500} X_i$ where $X_i$ is the annual claim size for policyholder $i$, then $$operatorname{E}[S] = 2500 * operatorname{E}[X_i] = 2500 * 1000 = 2500000,$$ and variance $$operatorname{Var}[S] = 2500 operatorname{Var}[X_i] =2500 * 900^2.$$

      We want to fins s (the premium income), such that $P(Sleq s)=0.999.$ This is equivalent to $P(Sgeq s)=0.001.$ By Chebyshev's inequality
      $$P(Sgeq s) = P(S-operatorname{E}[S]geq s- operatorname{E}[S])leq P(|S-operatorname{E}[S]|geq s-operatorname{E}[S])leq frac{operatorname{Var}[S]}{(s-operatorname{E}[S])^2}$$



      My question is how do we get the desired equality from this inequality? Thanks







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      asked Dec 7 at 21:24









      dxdydz

      1949




      1949






















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          I guess that the answer consists in solving the inequality:



          $$frac{operatorname{Var}[S]}{(s-operatorname{E}[S])^2} leq 0.001,$$



          which solution is:



          $$s geq sqrt{frac{operatorname{Var}[S]}{0.001}} + operatorname{E}[S]$$
          or
          $$s leq sqrt{frac{operatorname{Var}[S]}{0.001}} - operatorname{E}[S].$$



          So the solution is $ sqrt{frac{operatorname{Var}[S]}{0.001}} + operatorname{E}[S]$.






          share|cite|improve this answer





















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            1 Answer
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            active

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            0














            I guess that the answer consists in solving the inequality:



            $$frac{operatorname{Var}[S]}{(s-operatorname{E}[S])^2} leq 0.001,$$



            which solution is:



            $$s geq sqrt{frac{operatorname{Var}[S]}{0.001}} + operatorname{E}[S]$$
            or
            $$s leq sqrt{frac{operatorname{Var}[S]}{0.001}} - operatorname{E}[S].$$



            So the solution is $ sqrt{frac{operatorname{Var}[S]}{0.001}} + operatorname{E}[S]$.






            share|cite|improve this answer


























              0














              I guess that the answer consists in solving the inequality:



              $$frac{operatorname{Var}[S]}{(s-operatorname{E}[S])^2} leq 0.001,$$



              which solution is:



              $$s geq sqrt{frac{operatorname{Var}[S]}{0.001}} + operatorname{E}[S]$$
              or
              $$s leq sqrt{frac{operatorname{Var}[S]}{0.001}} - operatorname{E}[S].$$



              So the solution is $ sqrt{frac{operatorname{Var}[S]}{0.001}} + operatorname{E}[S]$.






              share|cite|improve this answer
























                0












                0








                0






                I guess that the answer consists in solving the inequality:



                $$frac{operatorname{Var}[S]}{(s-operatorname{E}[S])^2} leq 0.001,$$



                which solution is:



                $$s geq sqrt{frac{operatorname{Var}[S]}{0.001}} + operatorname{E}[S]$$
                or
                $$s leq sqrt{frac{operatorname{Var}[S]}{0.001}} - operatorname{E}[S].$$



                So the solution is $ sqrt{frac{operatorname{Var}[S]}{0.001}} + operatorname{E}[S]$.






                share|cite|improve this answer












                I guess that the answer consists in solving the inequality:



                $$frac{operatorname{Var}[S]}{(s-operatorname{E}[S])^2} leq 0.001,$$



                which solution is:



                $$s geq sqrt{frac{operatorname{Var}[S]}{0.001}} + operatorname{E}[S]$$
                or
                $$s leq sqrt{frac{operatorname{Var}[S]}{0.001}} - operatorname{E}[S].$$



                So the solution is $ sqrt{frac{operatorname{Var}[S]}{0.001}} + operatorname{E}[S]$.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Dec 7 at 22:32









                dallonsi

                1187




                1187






























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