Practice quiz6 and soln - Practice questions for Quiz 6 to...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Practice questions for Quiz 6 to be given on October 27 ______1. Suppose that X has mean μ =5 and σ =10 and Y= 6- 4X. The standard deviation of Y equals_____ _____2. Suppose that X 1 , X 2 and X 3 have mean μ =5 and σ 2 = 4 and Cov(X j , X k ) =0 for j k . Then the variance of Y= X 1 – X 2 + 2X 3 equals_______ 3-4. Suppose we take a random sample of n=4 values of X. We let X 1 denote the first value in the sample, X 2 denote the second value, X 3 denote the 3 rd value and X 4 denote the 4 th value. Given (1) μ 1 = μ 2 = μ 3 = μ 4 = μ x = 2 and (2) σ 1 = σ 2 = σ 3 = σ 4 2 x =9. Let 4 4 1 = = i i X X . _______ 3. Regardless of the value of N, the mean value of X equals____ ________ 4. If N>> 4 then Cov(X j , X k ) = 0 for all j ≠k and the X j are independent, so Var( X ) = ____ 1
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
SOLUTIONS TO QUIZ 4A ___ 40 ___ 1. Suppose that X has mean μ =5 and σ =10 and Y= 6- 4X. The standard deviation of Y equals_____ Y= 6-4X. If Y=aX + b then  σ 2 Y  = a 2 σ 2 x   and  σ =|a| σ Y Here a=-4,  so |a| =4,  and  σ x  =10. So  σ Y =|a| σ x =|-4|x10   = 40 . 24     ___     2. Suppose that X 1 , X 2 and X 3 have mean μ =5 and σ 2 = 4 and Cov(X j ,X k )=0 for j k . Then the variance
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern