Question

A boat travels 60 km downstream in 3 hours. What is the speed of the boat in still water if the river's speed is 5 km/h?

• A. 10 km/h
• B. 15 km/h
• C. 20 km/h
• D. 25 km/h

Hint:

For boat problems, use downstream speed = boat speed + river speed.

Answer 1

The Correct Option is B

The problem involves determining the speed of a boat in still water, given the downstream travel data and the river's current speed.

First, let's define the variables:

• Speed of the boat in still water = B km/h
• Speed of the river = 5 km/h
• Effective speed downstream = (Speed of the boat in still water + Speed of the river) = (B + 5) km/h

The boat travels 60 km downstream in 3 hours. Using the formula for speed, we have:

Speed = Distance/Time

So, the effective speed downstream:

(B + 5) = 60/3 = 20 km/h

Solving the equation for B:

B + 5 = 20

Subtract 5 from both sides:

B = 20 - 5

The speed of the boat in still water is:

B = 15 km/h

Therefore, the correct answer is 15 km/h, which matches the given correct option.