Question 19
Let $a_{1}, a_{2}, \ldots, a_{n}$ and $b_{1}, b_{2}, \ldots, b_{n}$ be two finite sequences consisting of $2n$ different real numbers. Rearranging each of the sequences in the increasing order we obtain $a_{1}^{\prime}, a_{2}^{\prime}, \ldots, a_{n}^{\prime}$ and $b_{1}^{\prime}, b_{2}^{\prime}, \ldots, b_{n}^{\prime}$. Prove that
$$
\max_{1 \leq i \leq n} \left| a_{i} - b_{i} \right| \geq \max_{1 \leq i \leq n} \left| a_{i}^{\prime} - b_{i}^{\prime} \right|.
$$
$$
\max_{1 \leq i \leq n} \left| a_{i} - b_{i} \right| \geq \max_{1 \leq i \leq n} \left| a_{i}^{\prime} - b_{i}^{\prime} \right|.
$$