2016-II-40
答案:D
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連接 $BD$。考慮 $\Delta PBD$,可得
$\begin{array}{rcll}
PD &
連接 $BD$。考慮 $\Delta PBD$,可得
$\begin{array}{rcll}
PD &
$\begin{array}{cl}
= & \dfrac{C^3_2C^9_
$\begin{array}{cl}
= & C^{20}_6 + C^{20}_
II 為正確。該分別的平均值及標準差分別為 $63.2
$\begin{array}{cl}
= & 4^2 \times 49 \\
=