Answer: D
According to the question: \[ \cfrac{4(p - 2) + 5(p + 1) + 7(p - 1)}{(p - 2) + (p + 1) + (p - 1)} = 5.4 \] \[ \Rightarrow \cfrac{4p - 8 + 5p + 5 + 7p - 7}{p - 2 + p + 1 + p - 1} = 5.4 \Rightarrow \cfrac{16p - 10}{3p - 2} = 5.4 \] \[ \Rightarrow 16.2p - 10.8 = 16p - 10 \Rightarrow 0.2p = 0.8 \Rightarrow p = 4 \]
According to the question: \[ \cfrac{4(p - 2) + 5(p + 1) + 7(p - 1)}{(p - 2) + (p + 1) + (p - 1)} = 5.4 \] \[ \Rightarrow \cfrac{4p - 8 + 5p + 5 + 7p - 7}{p - 2 + p + 1 + p - 1} = 5.4 \Rightarrow \cfrac{16p - 10}{3p - 2} = 5.4 \] \[ \Rightarrow 16.2p - 10.8 = 16p - 10 \Rightarrow 0.2p = 0.8 \Rightarrow p = 4 \]