Question:
Tick (✓) the correct answer:
A car takes 2 hours to reach a destination by travelling at 60 km/hr. How long will it take while travelling at 80 km/hr?
(a) 1 hr 30 min
(b) 1 hr 40 min
(c) 2 hrs 40 min
(d) none of these
Solution:
(a) 1 h 30 min
Let x h be the time taken by the car travelling at 80 km/hr.
The greater the speed, the lesser will be the time taken.
So, it is a case of inverse proportion.
Now, $60 \times 2=80 \times x$
$\Rightarrow x=\frac{120}{80}$
$\Rightarrow x=1.5$ Therefore, the car will take $1 \mathrm{~h} 30 \mathrm{~min}$ to reach its destination if it travels at a speed of $80 \mathrm{~km} / \mathrm{h} .$
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