Review question

What's the average speed of the second car? Add to your resource collection Remove from your resource collection Add notes to this resource View your notes for this resource

Ref: R7140

Solution

The winning car in a Grand Prix race covers the $\quantity{360}{km}$ course at an average speed of $\quantity{150}{km/h}$. The second car takes $6$ minutes longer than the first. Find the average speed of the second car.

As the first car has an average speed of $\quantity{150}{km/h}$, it needs $\frac{\quantity{360}{km}}{\quantity{150}{km/h}} = \quantity{2.4}{h}$ for the whole course.

Now the second car takes $\quantity{6}{min} = \quantity{0.1}{h}$ longer than the first car. Hence it needs $\quantity{2.5}{h}$ for the full course. This makes for an average speed of $\frac{\quantity{360}{km}}{\quantity{2.5}{h}} = \quantity{144}{km/h}.$