In a magnetic storage device, three attempts are made to read data before an error recovery procedure that repositions the magnetic head is used. The error recovery procedure attempts three repositionings before an “abort’’ message is sent to the operator. Let s denote the success of a read operation f denote the failure of a read operation F denote the failure of an error recovery procedure S denote the success of an error recovery procedure A denote an abort message sent to the operator.

Describe the sample space of this experiment with a tree diagram.

DeMorgan’s laws imply that Also, remember that 2-1.4 Counting Techniques (CD Only)

As sample spaces become larger, complete enumeration is difficult. Instead, counts of the number outcomes in the sample space and in various events are often used to analyze the random experiment. These methods are referred to as counting techniques and described on the CD.

EXERCISES FOR SECTION 2-1 A ¨ B  B ¨ A and A ´ B  B ´