Question

A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr, find the time taken by the boat to go 68 km downstream.

(a) 2 hours
(b) 3 hours
(c) 4 hours
(d) 5 hours

Answer 1

The time taken by the boat to go 68 km downstream is 4 hours.

Step-by-step explanation:

To find the time taken by the boat to go downstream, we need to consider the relative velocity of the boat with respect to the water. The boat's velocity in still water is 13 km/hr, and the velocity of the stream is 4 km/hr. When the boat is moving downstream, its velocity relative to the water is the sum of its velocity in still water and the velocity of the stream. So, the velocity of the boat downstream is 13 km/hr + 4 km/hr = 17 km/hr.

To find the time taken to travel 68 km downstream, we can use the formula:

Time = Distance / Velocity

Substituting the values, we get:
Time = 68 km / 17 km/hr = 4 hours