1. Criteria for tests concerning standard deviations.
Figure: 13-01a
Criteria for tests concerning standard deviations.

2. Criteria for tests concerning standard deviations.
Figure: 13-01b
Criteria for tests concerning standard deviations.

3. Criteria for tests concerning standard deviations.
Figure: 13-01c
Figure: 13-01c
Criteria for tests concerning standard deviations.

4. Figure: 13-02
Normal probability plot for Example 13.1 reproduced from display screen of TI-83 graphing calculator.

5. Criteria for tests concerning the equality of two standard deviations.
Figure: 13-03
Criteria for tests concerning the equality of two standard deviations.