Final answer:
The provided information does not clearly relate the value of 'z' to the index 'i=4', so an accurate answer cannot be given without further context.
Step-by-step explanation:
To find the value of z when a certain algorithm segment is executed with i=4, we look for the corresponding mathematical operation in the given information that specifically addresses the value of z with this index. The information relevant to z is as follows:
Since the index i is not clearly defined in connection with the given operations, it's not possible to confidently provide the exact value of z for the specified i=4 without further context. The listed operations seem unrelated to the concept of an index 'i'. Therefore, I must refrain from providing an incorrect answer.