what is the shortest possible time in which a bacterium could drift at a constant speed of 3.5mm/s across a petri dish with a diameter of 8.4cm

Answer 1

(8.4 cm)/(0.35 cm/s) = ___ seconds

I don't know why they call it the "shortest" time. It is the required time, if drifting at that speed across the dish along a diameter.

Answer 2

24s