Graph of \( \left(\frac{1}{v}\right) \) vs \( x \) for a particle under rectilinear motion is as shown, where \( v \) is velocity and \( x \) is position. The time taken by the particle to move from \( x = 4 \, \text{m} \) to \( x = 12 \, \text{m} \) is:
