In Exercise 6.1-7, lead concentrations near the San Diego

Chapter 6, Problem 10E

(choose chapter or problem)

In Exercise 6.1-7, lead concentrations near the San Diego Freeway in 1976 are given. During the fall of 1977, the weekday afternoon lead concentrations (in/m3) at the measurement station near the San Diego Freeway in Los Angeles were as follows:

9.5         10.7         8.3         9.8         9.1         9.4         9.6         11.9         9.5         12.6         10.5

8.9         11.4         12.0         12.4         9.9         10.9         12.3         11.0         9.2         9.3         9.3

10.5         9.4        9.4         8.2         10.4         9.3        8.7         9.8         9.1         2.9         9.8

5.7         8.2         8.1         8.8         9.7         8.1         8.8         10.3         8.6        10.2         9.4

14.8         9.9         9.3         8.2         9.9         11.6         8.7         5.0         9.9         6.3         6.5

10.2         8.8         8.0         8.7         8.9         6.8         6.6         7.3         16.7

(a) Construct a frequency distribution and display the results in the form of a histogram. Is this distribution symmetric?

(b) Calculate the sample mean and sample standard deviation.

(c) Locate ,  ± on your histogram. How many observations lie within one standard deviation of the mean? How many lie within two standard deviations of the mean?

(d) Using the data from Exercise 6.1-7 and the data from this exercise, construct a back-to-back stem-and-leaf diagram with integer stems in the center and the leaves for 1976 going to the left and those for 1977 going to the right.

(e) Construct box-and-whisker displays of both sets of data on the same graph.

(f) Use your numerical and graphical results to interpret what you see.