Final answer:
Using the provided information and setting up equations, we find that the speed of the stream is 3 km/h, and accordingly, the speed of the boat upstream is 24 km/h. Therefore, the correct answer is C. 24 km/h.
Step-by-step explanation:
To find the speed of a boat going upstream, we need to use the information that the boat's speed in still water is 9 times the speed of the stream, and the total time for a round trip journey is 4 hours and 3 minutes. Let's denote the speed of the stream as s km/h and the speed of the boat in still water as 9s km/h.
When the boat travels upstream, its effective speed decreases due to the opposing stream. The speed upstream is the boat's speed in still water (9s) minus the stream's speed (s), so upstream speed is 8s km/h. While going downstream, the stream aids the motion of the boat, and the downstream speed is the sum of the boat's speed in still water and the stream's speed, yielding 10s km/h.
To solve for s, we use the fact that the total distance traveled is 2 times 54 km (once upstream and once downstream) and the total time is 4 hours 3 minutes, which we convert to 4.05 hours for ease of calculation.
Time = Distance / Speed gives us two equations:
- Time upstream = 54 / 8s
- Time downstream = 54 / 10s
Adding both the upstream and downstream times should equal 4.05 hours:
54 / 8s + 54 / 10s = 4.05.
Upon solving the equation, we find that the value of s is 3 km/h. Hence, the speed of the boat upstream is 8s, which is 8 * 3 = 24 km/h.
The correct option is therefore C. 24.