Find the correct relationship between the given quantities: Quantity I: Distance covered in upstream in 10.8 hours Ratio of upstream speed to downstream speed is 1:11. If speed of boat in still water is 30 km/hr. Quantity II: Find x. The time taken by a boat for covering ‘x – 18’ km upstream is equal to time taken by it for covering ‘x’ km downstream. Upstream speed is 6 km/hr less than downstream speed and speed of boat in still water is 15 km/hr.

Quantity I: Boat speed = 30 km/hr, upstream:downstream = 1:11. Let upstream speed = x, then downstream = 11x. Also 30 = (x + 11x)/2 = 6x, so x = 5 km/hr. Upstream distance in 10.8 hours = 5 × 10.8 = 54 km. Quantity II: Let upstream speed = u, downstream = d. We have d - u = 6, u + d = 30 (since boat speed = 15), giving u = 12, d = 18. Time upstream = (x-18)/12, time downstream = x/18. Equating: (x-18)/12 = x/18, solving gives 3(x-18) = 2x, so 3x - 54 = 2x, x = 54. Then Quantity I = 54, Quantity II asks for x which is 54. They're equal, so relationship can be established.