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  • Variable transformation question

    Y = 10X^8

    Would someone walk me through the steps to get to X = .1Y^1.25 ?

    I see how X^8 = .1Y, but I'm not getting the next step to get me to .1Y^1.25.

    Thanks!

  • #2
    Originally posted by bubbarobert8 View Post
    Y = 10X^8

    Would someone walk me through the steps to get to X = .1Y^1.25 ?

    I see how X^8 = .1Y, but I'm not getting the next step to get me to .1Y^1.25.

    Thanks!
    Do you mean .125? And do you mean (.1Y)^(.125)?

    Comment


    • #3
      Originally posted by NoMoreExams View Post
      Do you mean .125? And do you mean (.1Y)^(.125)?
      That's what I thought he meant, too.

      Comment


      • #4
        I'm looking at problem 11 in the Actex manual, problem set 9. In the solution they step from P[10X^.8 <= y] to P[X <= (.1y)^1.25]. Sorry for the confusion.

        This problem has to do with variable transformation and I just started learning this material earlier this week. The problem states Y - 10X^.8. X is exponential with mean 1. We are asked to find f(y). I know they're using the cdf method to get to f(y), but I'm just not getting something here.

        Thanks!

        Comment


        • #5
          Originally posted by bubbarobert8 View Post
          I'm looking at problem 11 in the Actex manual, problem set 9. In the solution they step from P[10X^.8 <= y] to P[X <= (.1y)^1.25]. Sorry for the confusion.

          This problem has to do with variable transformation and I just started learning this material earlier this week. The problem states Y - 10X^.8. X is exponential with mean 1. We are asked to find f(y). I know they're using the cdf method to get to f(y), but I'm just not getting something here.

          Thanks!
          That's different than what you originally wrote since 8 is different from .8

          In any case, raise each side to 1/.8 power. You should know that (x^n)^(1/n) = x (obviously for even n you would want to take absolute value).

          Comment


          • #6
            Thank you NoMoreExams! I did not know that (x^n)^(1/n) = x.

            Pretty much all of this material including the calc and any associated algebra is self-taught. I haven't had any formal math classes, other than a statistical survey, in about 20 years.

            I really appreciate everyone on these discussion forums! Without your help it would be impossible for me to master this material.

            Comment


            • #7
              You should probably start off with more basic algebra before starting the actuarial exams. The stuff most of us students take for granted (ex. (x^n)^(1/n) = x), you are going to need to succeed. I would definitely skim over a high school algebra (late high school like grade 11-12 or better)) book before continuing if I were you. Just to make sure you understand the laws of powers, logarithms, trig identitites, and other stuff. You can master it while studying for P, but at least take a look some of those books on a weekend (maybe from a library) and hopefully your brain will be able to reaccess those ideas.

              FYI - I was out of school for about 9-10 years before becoming interested in actuarial science. This is what I did to make sure that I remembered the foundational rules, theorems, and tricks. Now I'm back in school, and I'm glad I reviewed my notes from high school. I was surprised that I actually kept them, too. It will be worth while. Trust me.

              Hope you succeed in your studying!

              Comment


              • #8
                Originally posted by bsd058 View Post
                You should probably start off with more basic algebra before starting the actuarial exams. The stuff most of us students take for granted (ex. (x^n)^(1/n) = x), you are going to need to succeed. I would definitely skim over a high school algebra (late high school like grade 11-12 or better)) book before continuing if I were you. Just to make sure you understand the laws of powers, logarithms, trig identitites, and other stuff. You can master it while studying for P, but at least take a look some of those books on a weekend (maybe from a library) and hopefully your brain will be able to reaccess those ideas.

                FYI - I was out of school for about 9-10 years before becoming interested in actuarial science. This is what I did to make sure that I remembered the foundational rules, theorems, and tricks. Now I'm back in school, and I'm glad I reviewed my notes from high school. I was surprised that I actually kept them, too. It will be worth while. Trust me.

                Hope you succeed in your studying!
                Believe it or not, a lot of "... for dummies" or cliffs notes books are really good in getting you to remember the material you learned that's that level.

                Comment


                • #9
                  Originally posted by NoMoreExams View Post
                  Believe it or not, a lot of "... for dummies" or cliffs notes books are really good in getting you to remember the material you learned that's that level.
                  Good point. It might be a better review than a high school textbook.

                  Comment


                  • #10
                    I couldn't agree more regarding the "... for dummies" books. The "Calculus For Dummies" was great and the "Probability for Dummies" was very helpful for the discrete and single variable continuous stuff.

                    Perhaps I should have elaborated a bit more on my math history. Regarding the calculus and probability I am completely self-taught, however, I learned how a nuclear power plant works in the Navy, Electrician's Mate; EM5 (back in the 90's while I was in my 20's) and now have an MBA with a concentration in Finance. My undergraduate is in accounting. I'm very comfortable with math in general, but have not learned a lot of the "tips and tricks" one learns for differentiation and anti-differentiation. I'm obviously still rusty on some algebra as well.

                    I was laid off 12/30/11 and started studying P/1 related material the week of Thanksgiving. I believe I'm getting a good grasp of the concepts, but hit stumbling blocks from time to time as I hit an area I don't remember or haven't encountered before.

                    As always, thanks to all who post on this site and others like it! It's great to see people helping each other toward a common goal!

                    Comment


                    • #11
                      Originally posted by bubbarobert8 View Post
                      I couldn't agree more regarding the "... for dummies" books. The "Calculus For Dummies" was great and the "Probability for Dummies" was very helpful for the discrete and single variable continuous stuff.

                      Perhaps I should have elaborated a bit more on my math history. Regarding the calculus and probability I am completely self-taught, however, I learned how a nuclear power plant works in the Navy, Electrician's Mate; EM5 (back in the 90's while I was in my 20's) and now have an MBA with a concentration in Finance. My undergraduate is in accounting. I'm very comfortable with math in general, but have not learned a lot of the "tips and tricks" one learns for differentiation and anti-differentiation. I'm obviously still rusty on some algebra as well.

                      I was laid off 12/30/11 and started studying P/1 related material the week of Thanksgiving. I believe I'm getting a good grasp of the concepts, but hit stumbling blocks from time to time as I hit an area I don't remember or haven't encountered before.

                      As always, thanks to all who post on this site and others like it! It's great to see people helping each other toward a common goal!
                      Just keep practicing. Review those books on algebra, and I'm sure you'll get it. I don't even have my bachelor's yet and I am doing well on the SOA questions. You should be able to pass with flying colors with your background!

                      Comment

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