Hicham runs $16 \mathrm{~km}$ in 1.5 hours. He runs the first $10 \mathrm{~km}$ at an average speed of $12 \mathrm{~km} / \mathrm{h}$. What is his average speed for the last $6 \mathrm{~km}$ ?
(A) $8 \mathrm{~km} / \mathrm{h}$
(B) $9 \mathrm{~km} / \mathrm{h}$
(C) $10 \mathrm{~km} / \mathrm{h}$
(D) $6 \mathrm{~km} / \mathrm{h}$
(E) $12 \mathrm{~km} / \mathrm{h}$
When Hicham runs $10 \mathrm{~km}$ at an average speed of $12 \mathrm{~km} / \mathrm{h}$, he takes $\frac{10}{12}=\frac{5}{6}$ hours to run this distance.

Since Hicham runs for a total of 1.5 hours, then he runs the last $6 \mathrm{~km}$ in $\frac{3}{2}-\frac{5}{6}=\frac{9}{6}-\frac{5}{6}=\frac{4}{6}=\frac{2}{3}$ hours.

Since he runs $6 \mathrm{~km}$ in $\frac{2}{3}$ hours, his average speed for this segment is $\frac{6}{2 / 3}=9 \mathrm{~km} / \mathrm{h}$.

ANsWER: (B)