If a boat goes 20 km upstream in 4 hours, what is the speed of the current if th

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Question: If a boat goes 20 km upstream in 4 hours, what is the speed of the current if the speed of the boat in still water is 10 km/h?

Options:

Correct Answer: 2 km/h

Solution:

Speed upstream = Speed of boat - Speed of current. Distance = 20 km, Time = 4 hours. Speed upstream = 20/4 = 5 km/h. Thus, 10 - x = 5, so x = 5 km/h.

If a boat goes 20 km upstream in 4 hours, what is the speed of the current if the speed of the boat in still water is 10 km/h?

If a boat goes 20 km upstream in 4 hours, what is the speed of the current if the speed of the boat in still water is 10 km/h?

Correct Answer: 5 km/h

Step 1: Identify the speed of the boat in still water, which is given as 10 km/h.
Step 2: Determine the distance traveled upstream, which is 20 km.
Step 3: Find the time taken to travel upstream, which is 4 hours.
Step 4: Calculate the speed upstream using the formula: Speed = Distance / Time. So, Speed upstream = 20 km / 4 hours = 5 km/h.
Step 5: Use the relationship between the speed of the boat, the speed of the current (let's call it x), and the speed upstream: Speed upstream = Speed of boat - Speed of current. This gives us the equation: 5 km/h = 10 km/h - x.
Step 6: Rearrange the equation to find the speed of the current: x = 10 km/h - 5 km/h.
Step 7: Calculate x: x = 5 km/h. Therefore, the speed of the current is 5 km/h.

Relative Speed – Understanding how the speed of a boat is affected by the current when moving upstream or downstream.
Distance, Speed, and Time Relationship – Applying the formula that relates distance, speed, and time to find unknown values.