Explanation

Let's analyze the statements to determine the validity of statement (iii).

Statement (i): The bulb X lasts longer than bulb Y.

X > Y

Statement (ii): The bulb Y does not last longer than bulb Z.

Y ≤ Z

Statement (iii): Bulb Z lasts longer than bulb X.

Z > X

Combining the information from statements (i) and (ii):

From (i): X > Y

From (ii): Y ≤ Z

To find if (iii) is true, we need to see if Z > X can be logically derived from the given statements:

Since X > Y and Y ≤ Z, we can deduce X > Y ≤ Z, which means X is greater than or equal to Z (X > Z is not necessarily true, but X > Y ≤ Z suggests X may or may not be greater than Z).

Therefore, without additional information, we cannot definitively conclude whether Z > X is based solely on statements (i) and (ii).

So, the answer is "Uncertain."