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!

95% CI for the population proportion

  1. Dec 6, 2008 #1
    1. The problem statement, all variables and given/known data

    A 95% CI for the population proportion of professional tennis players who earn more than $2 millions a year is found to be [0.82, 0.88]. Given this information the sample size that was used was approximately A) 545 B) 382 C) 233 D) 378
    Answer: A) 545


    2. Relevant equations

    Z = 1.96 for 95% CI
    +/- Z[S/sqrt(n)] = 0.03


    3. The attempt at a solution
    +/- 1.96 [0.03)/sqrt(n) = 0.03
    sqrt(n) = 1.96(2)/0.03
    sqrt(n) = 130
    n = 11.4 <-- this incorrect.

    The answer should be A) 545. But where did i go wrong? How do i solve this problem? Thanks.
     
  2. jcsd
  3. Feb 14, 2010 #2
    first use the fact that .03 = 2 *(1.96)*sqrt(p(1-p)/n) now solve for n and plug in the two bounds for the CI given. you will find that n lies between 450 and 630 hence the answer.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: 95% CI for the population proportion
  1. Population Proportion (Replies: 2)

  2. Population Model (Replies: 2)

  3. Population and limits (Replies: 2)

  4. Population model (Replies: 1)

Loading...