Questions: A boat travels a total distance of 150 km in a time of 20 hours.
iii Calculate the average speed of the boat.
iv For more than half of the time that the boat was travelling, its speed was 12 km/h. Explain the difference between this speed and your answer to (part i).
[Total: 6]
Transcript text: d A boat travels a total distance of 150 km in a time of 20 hours.
iii Calculate the average speed of the boat.
[2]
$\qquad$ $\qquad$
iv For more than half of the time that the boat was travelling, its speed was $12 \mathrm{~km} / \mathrm{h}$.
Explain the difference between this speed and your answer to (part $\mathbf{i}$ ).
[2]
$\qquad$ $\qquad$
[Total: 6]
Solution
Solution Steps
Step 1: Calculate the Average Speed of the Boat
The average speed of the boat can be calculated using the formula for average speed:
Step 2: Explain the Difference Between the Given Speed and the Average Speed
The problem states that for more than half of the time, the boat was traveling at a speed of \(12 \text{ km/h}\). This means that for the remaining time, the boat must have been traveling at a speed lower than \(7.5 \text{ km/h}\) to bring the overall average speed down to \(7.5 \text{ km/h}\).
The average speed is a weighted average of the different speeds the boat traveled at different times. Since the boat traveled at \(12 \text{ km/h}\) for more than half of the time, it must have traveled at a significantly lower speed for the remaining time to achieve an overall average speed of \(7.5 \text{ km/h}\).