2010-II-15

答案：B
$10\text{ kg}$ 混合茶葉的總成本

$\begin{array}{cl}
= & \$80 \times 4 + \$40 \times 6 \\
= & \$560
\end{array}$

所以，混合茶葉的成本

$\begin{array}{cl}
= & \$560 \div 10 \\
= & \$56 \text{/kg}
\end{array}$