Normal Distribution and the Standard Deviation

The GeoGebra applet contains a random normal distribution with 100 data points.
  1. Randomize the data at least 10 times. What do you notice about the shape of the distribution? Share with a classmate.
    1. Use the movable lines to estimate the location of -1 stdev, the mean, and +1 stdev in the distribution. How did you decide where to put the lines? Click in the Show Statistics checkbox and compare your estimates to the actual +/-1 stdev range.
    2. Hide the statistics and repeat step (a) at least ten more times.
    3. Did you change your strategy? Explain.
  2. Position the movable lines at the ends of the +/-1 stdev range.
    1. Estimate the number of data points captured in the +/-1 stdev range. Click on the Show Count checkbox and compare the actual count to your estimate.
    2. Hide the count information and repeat step (a) at least ten more times. What do you notice?
    3. If a normal distribution has 1,000 points, what percentage would you expect to be in the +/-1 stdev range? Explain.