Consider positive numbers a1 ≥ a2 ≥ a3 and b1 ≥ b2 ≥ b3. If Σ ai = 12 and Σ bi = 18, then the minimum possible value of a1b3 + a2b2 + a3b1 according to Chebyshev's sum inequality is:

The inequality |x| ≥ 5 implies that:

If |x - 4| + |x - 2| < 4, find the solution set for x.

If a, b, c and p, q, r are real numbers such that a ≥ b ≥ c and p ≥ q ≥ r, then according to Chebyshev's sum inequality, which of the following is true?