Instruction: Each problem consists of a question followed by two statements. Decide whether the data in the statements are sufficient to answer the question. If \(xy < yz < 0\), is \(y > 0\)? (1) \(x < z\). (2) \(x < 0\).

Explanation: (A) Given: \(xy < yz < 0\). The condition \(yz < 0\) means y and z have opposite signs. The condition \(xy < yz\) means \(xy - yz < 0 \implies y(x - z) < 0\). (1) If \(x < z\), then \(x - z < 0\). For \(y(x - z) < 0\) to be true, if \(x-z\) is negative, \(y\) must be positive. This guarantees \(y > 0\). So (1) is sufficient. (2) If \(x < 0\). If y is positive, \(y > 0\). Example: \(x = -5, y = 2, z = -1 \implies -10 < -2 < 0\). Yes, \(y > 0\). If y is negative, \(y < 0\). Example: \(x = -5, y = -2, z = 1 \implies 10 < -2 < 0\). No. Since the answer can be yes or no, (2) is not sufficient. Thus, (1) alone is sufficient.