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P1 Discussion May 2008!

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  • P1 Discussion May 2008!

    It's ok to dicuss the exam now...the mods said ok. Anyone get a
    Bayes questions for their first? Something about finding the p of Female smokers?
    Last edited by edt966; May 19 2008, 11:45 PM.

  • #2
    Go

    It's funny, I just realized I don't remember any of my questions except for something with a quadratic similar to:

    2X - X^2 < 1

    with a standard normal.


    /racks brain
    ________
    Aprilia RS50
    Last edited by prufer; January 21 2011, 12:55 PM.
    :Waldo:

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    • #3
      Go

      Okay, another one. A and B are mutually exclusive. C and D are mutually exclusive.

      P(A) given
      P(C) given?
      P(A intersect C) given

      Find P(B intersect D).


      I thinkkk that was it.
      ________
      Triumph Model R
      Last edited by prufer; January 21 2011, 12:55 PM.
      :Waldo:

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      • #4
        what i remember

        i had a gamma question, no weibul pareto lognormal beta or chi square.
        one mgf
        no multivariate transformation or bivariate normal
        a lot of bivariate discretes, way more than I expected, but they were ok
        im blanking on the rest

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        • #5
          There's always a question or two that I ponder after the test. I think I may have to break out the calculator and filler paper once more before taking a break. :unsure:

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          • #6
            Go

            Oh oh oh! Did anyone get one about a mgf that listed three properties and asked which must be true? And the choices were something like

            a) i and ii
            b) ii and iii
            c) i and ii and iii
            d) ii and iii
            e) i and iii


            ?
            ________
            trichome
            Last edited by prufer; January 21 2011, 12:56 PM.
            :Waldo:

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            • #7
              Hey Prufer, I had both those questions.

              The only other question I remember for sure (because it was short) was: Two people arrange to meet sometime between 4 and 5 pm. They each arrive at different times. What's the probability that the first person to arrive will have to wait at least 20 minutes for the other person?

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              • #8
                Originally posted by prufer View Post
                Oh oh oh! Did anyone get one about a mgf that listed three properties and asked which must be true? And the choices were something like

                a) i and ii
                b) ii and iii
                c) i and ii and iii
                d) ii and iii
                e) i and iii


                ?
                oh yea. i did get one like that too.

                Also i got one where you have X following a normal distribution of mean 5 and standard deviation 1 or something, and then you have to find the probability that 8X - X^2 < 1. I didn't know how to do this one...

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                • #9
                  Go

                  Originally posted by cron View Post
                  oh yea. i did get one like that too.

                  Also i got one where you have X following a normal distribution of mean 5 and standard deviation 1 or something, and then you have to find the probability that 8X - X^2 < 1. I didn't know how to do this one...

                  I think I had st.dev. = 2. I set the inequality equal to 0 and used the quadratic formula to find the two values of X. Then I plugged both of those into the standard normal equation with whatever it fit into, > or <, and added (or subtracted, I forgot) the two numbers I got from the chart. Not sure if it was the right thing to do, though!
                  ________
                  Toyota Supra
                  Last edited by prufer; January 21 2011, 12:56 PM.
                  :Waldo:

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                  • #10
                    Go

                    I also remember one that wasn't too complicated once you sifted through the odd explanation. It was about a town with the city hall located at the origin, and residents could only walk to the building in parallel lines to the x- and y-axis. I think it asked you to find the expected value of the distance traveled by a resident.
                    ________
                    buy silver surfer
                    Last edited by prufer; January 21 2011, 12:56 PM.
                    :Waldo:

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                    • #11
                      Hmm I can only remember the simpler ones. I had a question that stated 4 people were wearing hats. If each takes off their hat and randomly puts back on a hat, what is the probability that none of the four are wearing their original hat?

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                      • #12
                        Originally posted by prufer View Post
                        I also remember one that wasn't too complicated once you sifted through the odd explanation. It was about a town with the city hall located at the origin, and residents could only walk to the building in parallel lines to the x- and y-axis. I think it asked you to find the expected value of the distance traveled by a resident.
                        I had that as my last question. I could've sworn that they threw in something about the population density varying with the distance from city hall as well. That really threw me off.

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                        • #13
                          Go

                          Originally posted by irvineposse View Post
                          Hmm I can only remember the simpler ones. I had a question that stated 4 people were wearing hats. If each takes off their hat and randomly puts back on a hat, what is the probability that none of the four are wearing their original hat?

                          Me too!


                          ...
                          ________
                          Honda ZB50
                          Last edited by prufer; January 21 2011, 12:56 PM.
                          :Waldo:

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                          • #14
                            Originally posted by prufer View Post
                            Oh oh oh! Did anyone get one about a mgf that listed three properties and asked which must be true? And the choices were something like

                            a) i and ii
                            b) ii and iii
                            c) i and ii and iii
                            d) ii and iii
                            e) i and iii


                            ?
                            I had that...I think 2 of them were correct. I know that C*Mx(t) is not a mgf.

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                            • #15
                              Originally posted by prufer View Post
                              Okay, another one. A and B are mutually exclusive. C and D are mutually exclusive.

                              P(A) given
                              P(C) given?
                              P(A intersect C) given

                              Find P(B intersect D).


                              I thinkkk that was it.
                              Yeah that's it. Did you get an answer for it? I got 0.05 but it was weird how I got it. My thoughts were A= AandC + AandD; B= BandC + BandD; The question said A or B has to happen and C or D has to happen.

                              Therefore
                              P(A')=P(B) and P(C')=P(D). I was a little unsure about it.

                              I didn't have a single Bayes, just a bunch of "find the cdf for". I actually had a bunch of tricky deductible problems, I don't remember what they are.

                              Oh did anyone have this...
                              N is distributed Poisson with variance lambda. Lambda is uniformly distributed over [0,3]. What is the mean of N?
                              Answers: A)lambda B)2*Lambda C) 1 D) 1.5 E) 3

                              I picked A). I was confused because it seemed to easy.
                              Last edited by Charles.Lindberg; May 20 2008, 10:03 AM.

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