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Normal Distribution: Basic statistics help needed!

  1. Apr 16, 2012 #1
    1. The problem statement, all variables and given/known data

    In math 334 one semester, the average student made 1200 computations per month with a standard deviation of 150 computations. Assume that the number of computations is approximated by a normal curve. Find the percent of students making between 1200 and 1600 computations a month.

    2. Relevant equations
    standard bell curve equation. I don't really know what specific ones I'm supposed to use for a problem like this.


    3. The attempt at a solution
    I figured that the answer would have to be the prob. of a student making less than 1200* the prob of a student making less than 1600. Which would be 1/2*prob of making less than 1600, which I can't seem to figure out.
     
  2. jcsd
  3. Apr 16, 2012 #2

    NascentOxygen

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    Staff: Mentor

    Last edited: Apr 16, 2012
  4. Apr 16, 2012 #3

    HallsofIvy

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    Times? Try subtracting.

    If z has the normal distribution with mean [itex]\mu[/itex] and standard deviation [itex]\sigma[/itex] then [itex](z- \mu)/\sigma[/itex] has the standard normal distribution for which you probably have tables (a good one is at http://www.math.unb.ca/~knight/utility/NormTble.htm [Broken]).
     
    Last edited by a moderator: May 5, 2017
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