MA 123 Quiz 1
Spring, 2009

Name:  _________________________________________________

  1. The following numbers represent the length, in millimeters, of several earth worms:  35  37  39  41  42  53  61  75  107.

    1. (4 pts) Give a stemplot of the data.







    2. (3 pts) Why would a five-number summary of the data be better than using the mean and standard deviation?





    3. (4 pts) Calculate (and give) the first and third quartiles (don't forget the unit of measure).





    4. (3 pts) According to the 1.5 * IQR rule, should you suspect any of these measurements to be outliers?  If so, which ones?





  2. Suppose a manufacturer sees that the diameters of the basketballs it manufactures are normally distributed with a mean μ = 9.4 inches and a standard deviation  σ  = 0.1 inches.

    1. (3 pts) What is the z-score for 9.3 inches?




    2. (3 pts)  What percentage of basketballs manufactured by this company will have diameters less than 9.3 inches?