If a boat can travel 60 km downstream in 3 hours, and the speed of the stream is

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Question: If a boat can travel 60 km downstream in 3 hours, and the speed of the stream is 6 km/h, what is the speed of the boat in still water?

Options:

Correct Answer: 20 km/h

Solution:

Let the speed of the boat in still water be y km/h. Downstream speed = y + 6 km/h. Therefore, (y + 6) * 3 = 60. Solving gives y = 18 km/h.

If a boat can travel 60 km downstream in 3 hours, and the speed of the stream is 6 km/h, what is the speed of the boat in still water?

If a boat can travel 60 km downstream in 3 hours, and the speed of the stream is 6 km/h, what is the speed of the boat in still water?

Correct Answer: 18 km/h

Step 1: Understand that the boat travels downstream, which means it is aided by the speed of the stream.
Step 2: The speed of the stream is given as 6 km/h.
Step 3: Let the speed of the boat in still water be represented as 'y' km/h.
Step 4: When the boat is going downstream, its effective speed is the speed of the boat plus the speed of the stream, which is (y + 6) km/h.
Step 5: We know the boat travels 60 km downstream in 3 hours.
Step 6: Use the formula: Distance = Speed × Time. Here, Distance = 60 km and Time = 3 hours.
Step 7: Substitute the effective speed into the formula: 60 = (y + 6) * 3.
Step 8: Simplify the equation: 60 = 3y + 18.
Step 9: Rearrange the equation to isolate 'y': 3y = 60 - 18.
Step 10: Calculate: 3y = 42, then divide by 3 to find y: y = 14 km/h.
Step 11: Therefore, the speed of the boat in still water is 18 km/h.

Relative Speed – Understanding how the speed of a boat is affected by the current of the stream.
Algebraic Manipulation – Solving equations to find the unknown variable, in this case, the speed of the boat in still water.