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!

Small Sample Size

  1. Dec 5, 2010 #1
    [tex]\begin{tabular}{lcr}
    418 & 421 & 422 & 425& 427 & 431 \tabularnewline
    434 & 437 & 439 & 446 & 447 & 448 & 453 \tabularnewline
    454 & 463 & 465
    \end{tabular}[/tex]

    1. Calc the sample mean and sample standard deviation. [tex]\sum_{i=1}^{17} x_i=7451[/tex] and [tex]\sum_{i=1}^{17} x_i^2=3269399[/tex]

    n=17 [tex]\overline{x}=\frac{7451}{17}=438.29[/tex]

    s^2=[tex]\frac{17(\frac{3269399}{17}*(438.29)^2}{16}=\sqrt{233.18}=15.27[/tex]


    2. Assuming that the population of degree polymerization has a normal dist, construct a 90% CI for the pop mean degree of polymerization.

    [tex]438.29 \pm T_{.10/2,n-1}*\frac{15.27}{\sqrt{17}}[/tex]
    [tex]438.29 \pm 1.746*\frac{15.27}{\sqrt{17}}[/tex]
    [tex]438.29 \pm 6.466[/tex]
    (431.82,444.76)

    3. If the value 418 in the original data was 518 instead, would the interval in question 2 be wider or narrower? Explain

    I was wondering if I had interpreted this correctly. I answered:

    The interval would be (434.14,454.21)

    w=width
    Since w/2 = [tex]\alpha / 2 * \sigma / \sqrt{n}[/tex], we can say that since the sample sd increased the width increased as well.
     
  2. jcsd
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: Small Sample Size
Loading...