Final answer:
The kayak's effective speed downstream is 14 km/h (11 km/h kayak speed + 3 km/h current speed). It will take 2.5 hours to travel 35 km downstream.
Step-by-step explanation:
The student's question is about calculating the time needed for a kayak to travel 35 km downstream on a river.
The kayak travels at 11 km/h in still water, and the river's current flows at a rate of 3 km/h.
To find the time taken to travel downstream, we need to add the kayak's speed and the current's speed to get the effective speed of the kayak going downstream.
The kayak's speed in still water is 11 km/h, and the speed of the river current is 3 km/h.
When going downstream, these speeds add up, so the effective speed of the kayak is :
11 km/h + 3 km/h
= 14 km/h.
Next, to find out how long it will take to travel the 35 km downstream, we use the formula:
time = distance / speed
In this case:
time = 35 km / 14 km/h
= 2.5 hours
Therefore, it will take the kayak 2.5 hours to travel 35 km downstream.