250/5/8 = 250 × (8/5)
= 400
So, a sloth may move 400 units per hour.
In other words, a sloth may move in 400 units per 60 minutes.
So, it will move [tex]\frac{400}{2}[/tex] = 200 units per 30 minutes.
Therefore, it will move (400 + 200) units per (60 + 30) minutes.
Hence, in 90 minutes, the sloth may move 600 units.
