Data Sufficiency (DS) | Re: If pqr < 0 < pqs, is q < 0

Notice none of the letters can be zero, so each is either positive or negative.

From the stem we know that pqr < 0, so we know (pr)(q) < 0, and pr and q must have opposite signs. If, from Statement 1, pr is positive, then q must be negative, and Statement 1 is sufficient.

If we multiply the inequality in Statement 2 by q on both sides, then if q is positive, we'll leave the inequality alone, and if q is negative, we'll reverse the inequality. So if q were positive, pqr > pqs would need
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