87670 \(A \equiv(2,3,-2)\) and \(B \equiv(4,1,-2)\) are two vertices of \(\triangle A B C . P, Q\) and \(R\) are the midpoints of \(A B\), \(B C\) and \(A C\) respectively. The coordinates of \(R\) are \(\left(\frac{5}{2}, \frac{5}{2},-\frac{7}{2}\right)\). Then the centroid of \(\triangle P Q R\) is
87670 \(A \equiv(2,3,-2)\) and \(B \equiv(4,1,-2)\) are two vertices of \(\triangle A B C . P, Q\) and \(R\) are the midpoints of \(A B\), \(B C\) and \(A C\) respectively. The coordinates of \(R\) are \(\left(\frac{5}{2}, \frac{5}{2},-\frac{7}{2}\right)\). Then the centroid of \(\triangle P Q R\) is
87670 \(A \equiv(2,3,-2)\) and \(B \equiv(4,1,-2)\) are two vertices of \(\triangle A B C . P, Q\) and \(R\) are the midpoints of \(A B\), \(B C\) and \(A C\) respectively. The coordinates of \(R\) are \(\left(\frac{5}{2}, \frac{5}{2},-\frac{7}{2}\right)\). Then the centroid of \(\triangle P Q R\) is
87670 \(A \equiv(2,3,-2)\) and \(B \equiv(4,1,-2)\) are two vertices of \(\triangle A B C . P, Q\) and \(R\) are the midpoints of \(A B\), \(B C\) and \(A C\) respectively. The coordinates of \(R\) are \(\left(\frac{5}{2}, \frac{5}{2},-\frac{7}{2}\right)\). Then the centroid of \(\triangle P Q R\) is