speed of the bacterium is 3.5 mm/s
[tex]v = 3.5 mm/s[/tex]
total distance traveled by bacterium = 8.4 cm
[tex]d = 8.4 cm = 84 mm[/tex]
time take to cover the distance
[tex]t = \frac{d}{v}[/tex]
[tex]t = \frac{84}{3.5} = 24 s[/tex]
so it will take 24 s to move this distance
