Question:
Mark (✓) against the correct answer:
A car is travelling at an average speed of 60 km per hour. How much distance will it cover in 1 hour 12 minutes?
(a) 50 km
(b) 72 km
(c) 63 km
(d) 67.2 km
Solution:
(b) 72 km
Let x km be the distance covered in 1 h 12 min.
Now, 1 h 12 min = (60+12) min = 72 min
More distance will be covered in more time.
So, it is a cas of direct proportion.
Now, $\frac{60}{60}=\frac{x}{72}$
$\Rightarrow x=72 \mathrm{~km}$
$\therefore$ The car will cover a distance of $72 \mathrm{~km}$ in $1 \mathrm{~h} 12 \mathrm{~min}$.