1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Chebyshev's theorem (statistics)

  1. Sep 20, 2008 #1
    1. The problem statement, all variables and given/known data
    If 100 students take a quiz, use chebyshev's theorem to predict the number of students plus and minus 2 standard deviations from the mean.

    2. Relevant equations
    1-1/k^2 where k is standard deviations

    3. The attempt at a solution
    I think its 75, but I'm not sure...I'm just trying to get this concept down
  2. jcsd
  3. Sep 20, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    Don't just memorize formulas, learn what they say! Did you notice that "1- 1/k2" is not even an equation? What is equal to 1- 1/k2?

    1- 1/22= 1- 1/4= 3/4. 3/4 of 100= 75. Now, if "the fraction of trials within k standard deviations of the mean" is what 1- 1/k2 gives, you are completely correct!
    Last edited: Sep 21, 2008
  4. Sep 20, 2008 #3


    User Avatar
    Homework Helper

    Chebyshev's Theorem does indeed state give the percentage data you can expect to find within [tex] \pm k [/tex] standard deviations of the mean, as long as [tex] k > 1 [/tex] (and it is here.
    However, remember that technically the answer is a lower bound, so you the proper response not that the percentage is [tex] 75\% [/tex], but that it is at least [tex] 75\% [/tex].
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Chebyshev's theorem (statistics)
  1. Statistics for a $ (Replies: 1)

  2. Chebyshev's theorm (Replies: 2)

  3. Chebyshev's theorem (Replies: 2)