1. Limited time only! Sign up for a free 30min personal 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!

Find 'k' (# of standard deviations from the mean)

  1. Mar 5, 2012 #1
    1. The problem statement, all variables and given/known data
    μ=10 σ^2=4

    I seem to be getting the first two just time the same as i get every other problem, but I can't seem to get C)'s 'k'. typically i will take the absolute value of the portion that we are looking at, i.e. P(-10<X<10) would be |-10+10| = 20, divide that by two to get the center, 20/2 = 10 and then divide that by the standard deviation, which for this problem is 2. So 10/2 = 5, which i use for K. It's worked for every problem so far, but for C) they have 2.5 instead of (5/4) that i get. Any ideas?

    vkg78.png


    2. Relevant equations

    P(μ−kσ<X<μ+kσ)≥1− 1/k^2

    3. The attempt at a solution
     
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted