The position vectors of the vertices P,Q and R of ∆PQR are -i ̂+2j ̂+4k ̂, 3i ̂+6j ̂+8k ̂ and 4i ̂+j ̂+k ̂ respectively.
Which of the following is the vector that represents the median (PS) ?
A. 7/2 i ̂+9/2 j ̂+9/2 k ̂
B. 2i ̂+3j ̂+13/3 k ̂
C. 9/2 i ̂+3/2 j ̂+1/2 k ̂
D. -1/2 i ̂+5/2 j ̂+7/2 k ̂