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!

Finding sample size given info on confidence interval

  1. Jun 28, 2014 #1
    1. The problem statement, all variables and given/known data

    Suppose that an investigator believes that virtually all values in the population are between 38 and 70. The appropriate sample size for estimating the true population mean within 2 units with 95% confidence level is approximately how much?

    2. Relevant equations


    Variance of the sampling distribution of size n = Variance of the population distribution / n

    3. The attempt at a solution


    I think I'm solving
    1.96(SD of the sampling distribution of size n)=2

    But I don't think there's any information given on the population variance so I don't know what to do.
     
  2. jcsd
  3. Jun 28, 2014 #2
    Worst case, half the population values are 38 and half are 70. What's the variance in that case?
     
  4. Jun 29, 2014 #3

    pasmith

    User Avatar
    Homework Helper

    Use the three standard deviation rule.
     
  5. Jun 29, 2014 #4
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Finding sample size given info on confidence interval
  1. Confidence Interval (Replies: 1)

Loading...