I’m came across this question from ETS Quant Practice test.

The question states that the averages of lists X and Y are equal. In the solution explanation, they solve for s in terms of t and say s could be negative, zero, or positive, leading to answer **D (indeterminate)**.

My question: Since X is a list (therefore should be ordered) and s is listed after 5 in X, shouldn’t s be always positive? Or it’s only when they clearly state that a list is ordered that we can consider it to be in order ?