Final answer:
The given information is insufficient to determine the speed of the boat in still water.
Step-by-step explanation:
To find the speed of the boat in still water, we can use the concept of relative velocity. Let's denote the speed of the boat in still water as 'b' km/h.
When the boat is traveling downstream, the speed of the boat is equal to the sum of its speed in still water and the speed of the stream. So, the speed of the boat downstream is (b + 5) km/h.
When the boat is traveling upstream, the speed of the boat is equal to the difference between its speed in still water and the speed of the stream. So, the speed of the boat upstream is (b - 5) km/h.
According to the given information, the boat can travel a certain distance downstream in 3 hours and can return to the starting point in 4 hours.
Using the formula distance = speed × time, we can write two equations:
3(b + 5) = d (equation 1)
4(b - 5) = d (equation 2)
Here 'd' represents the distance.
Simplifying both equations, we get:
3b + 15 = d (equation 3)
4b - 20 = d (equation 4)
Equating equations 3 and 4, we have:
3b + 15 = 4b - 20
b + 15 = -20
b = -35
However, the speed of the boat cannot be negative. So, we discard this value.
Hence, there is no possible solution and we cannot determine the speed of the boat in still water with the given information.