Question

Roger Waters can scrape up just enough money to rent a canoe for 1 hour and 30 minutes. If he paddles out on a lake at 4 kph and returns at 2 kph, how far will he have paddled the canoe?
Which of the following is a true statement based on this problem?

Answer 1

Answer:

The distance paddling out on a lake is 2 kilometres and the distance returning back is also 2 kilometres. In total, 4 kilometres.

Step-by-step explanation:

Let t hours be the time it takes Roger to puddle out on a lake. Then $\left(1\dfrac{1}{2}-t\right)$ hours is the time it takes him to return (note that 1 hour and 30 minutes is exactly $1\dfrac{1}{2}$ hours).

1. If he paddles out on a lake at 4 kph for t minutes, then the distance is

$4\cdot t=4t\ km.$

2. If he  returns at 2 kph, then the distance is

$2\cdot \left(1\dfrac{1}{2}-t\right)=3-2t\ km.$

3. These distances are the same, thus

$4t=3-2t,\\ \\6t=3,\\ \\t=\dfrac{1}{2}\ hour.$

The distance paddling out on a lake is 2 kilometres and the distance returning back is also 2 kilometres. In total, 4 kilometres.