Question

A boat travelling at top speed upstream moves at 15 km/hr. When it travels downstream, again at top speed, it moves at 25 km/hr. What is the boat’s top speed in still water? a. 15 km/hr b. 20 km/hr c. 25km/hr d. 30 km/hr

Answer 1

The boat’s top speed in still water is calculated by averaging its upstream and downstream speeds, which results in a speed of 20 km/hr. Hence, the correct answer is (b) 20 km/hr.

Step-by-step explanation:

The boat's top speed in still water can be determined by calculating the average of its upstream and downstream speeds. When traveling upstream, the boat's speed is reduced by the speed of the current, while downstream, the speed of the current is added to the boat's speed. Thus, the top speed of the boat in still water is the intermediate value between the upstream and downstream speeds.

Given:

• Upstream speed = 15 km/hr (boat speed - current speed)
• Downstream speed = 25 km/hr (boat speed + current speed)

To calculate the speed of the boat in still water, we use the following equation:

Speed of the boat in still water = (Upstream Speed + Downstream Speed) / 2

Substitute the given values:

Speed of the boat in still water = (15 km/hr + 25 km/hr) / 2

Speed of the boat in still water = 20 km/hr

Therefore, the correct answer is (b) 20 km/hr.