A fisherman traveled in a boat from point N upstream. After having traveled 6 km, he stopped rowing and 4 hour 30 min after first leaving N, he was brought back to N by the current. Knowing that the speed of the boat in still water is 90 km/hour, find the speed of the river’s current.
since time = distance/speed,
6/(90-x) + 6/x = 4.5
x ≈ 1.35 km/hr
This answer is incorrect
x=2
I have the Same question, and both answers are wrong
Current is 4.5km/h
4.5 is right
To find the speed of the river's current, we can set up an equation involving the distance, time, and speed.
Let's denote the speed of the river's current as 'c' km/hour.
When the fisherman rows upstream, the effective speed of the boat is the speed of the boat in still water minus the speed of the current, which is (90 - c) km/hour.
The fisherman traveled 6 km upstream, and we can determine the time it took for this journey using the formula:
time = distance / speed.
So, the time taken to travel 6 km upstream is:
time = 6 km / (90 - c) km/hour.
After having traveled 6 km upstream, the fisherman stops rowing and is brought back to point N by the current. This time, the effective speed of the boat is the speed of the boat in still water plus the speed of the current, which is (90 + c) km/hour.
The time taken to travel back to point N is given as 4 hours 30 minutes, which can be converted to 4.5 hours.
So, we can set up the equation:
4.5 hours = 6 km / (90 + c) km/hour.
To find the speed of the river's current 'c', we need to solve this equation.
First, let's simplify the equation:
4.5(90 + c) = 6
Now, we can solve for 'c':
405 + 4.5c = 6
Subtracting 405 from both sides, we get:
4.5c = 6 - 405
Simplifying further:
4.5c = -399
Finally, divide both sides by 4.5 to solve for 'c':
c = -399 / 4.5
c ≈ -88.67
Since the speed of the river's current cannot be negative, we ignore the negative sign. Therefore, the speed of the river's current is approximately 88.67 km/hour.