Figure 1 shows the mean distance between separating sister chromatids during mitosis in a plant cell.

Calculate the rate of separation of the sister chromatids during Stage II.
During Stage II, the mean distance increases from 3.8 μm3.8\ \mu\text{m}3.8 μm at 800 s to 21.5 μm21.5\ \mu\text{m}21.5 μm at 1700 s.
Give your answer in μm⋅minute−1\mu\text{m}\cdot\text{minute}^{-1}μm⋅minute−1 and to 3 decimal places.