Using the telephone numbers
listed in your local directory as your population, randomly obtain
20 samples of size 3. From each telephone number identified as a
source, take the fourth, fifth, and sixth digits.

1. Calculate the mean of the
   20      samples
2. Draw a histogram showing
   the 20      sample means. (Use classes
   -0.5 to 0.5, 0.5 to 1.5, 1.5 to 2.5 and so on).
3. Describe the distribution
   of      the x-bars that you see in part b
   (shape of distribution, center, and the
        amount of dispersion).
4. Draw 20 more samples and
   add      the 20 new x-bars to the
   histogram in part b. Describe the distribution
        that seems to be
   developing.