A boat running upstream takes 528 min to cover a certain distance, while it takes 240 min to cover the same distance running downstream. What is the ratio between the speed of the water current, respectively?

Let boat's rate upstream be U and boat's rate downstream = V
According to the question.
Distance covered in 528 min = Distance covered in 240 min
⇒ Distance covered in 8 h 48 min = Distance covered in 4 h
⇒ U x 8⁴/₅ = V x 4
⇒ (44 x U)/5 = 4V
⇒ V = (11 x U)/5
∴ Required ratio = (V + U)/2 : (V - U)/2
⇒ = (11U/5 + U)/2 : (11U/5 - U)/ 2
⇒ = 16U/5 : 6U/5 = 8 : 3