Question:
A car is travelling at the average speed of 50 km/hr. How much distance would it travel in 1 hour 12 minutes?
Solution:
Let x km be the required distance. Then, we have:
$1 \mathrm{~h}=60 \mathrm{~min}$
i. e., $1 \mathrm{~h} 12 \mathrm{~min}=(60+12) \mathrm{min}=72 \mathrm{~min}$
| Distance covered (in km) | 50 | x |
| Time (in min) | 60 | 72 |
Clearly, more distance will be covered in more time.
So, this is a case of direct proportion.
Now, $\frac{50}{60}=\frac{x}{72}$
$\Rightarrow x=\frac{50 \times 72}{60}$
$\Rightarrow x=60$
Therefore, the distance travelled by the car in 1 h 12 min is 60 km.