Question

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

Answer 1

Let time taken will be x hrs

Speed 60 km/h : 80 km/h

Time taken to 2hr : x

reach

(More speed, less time)

By inverse proportion

60 : 80 : : x : 2

$x=\frac{60\times 2}{80}=\frac{3}{2}$

$\therefore$ Time take $\frac{3}{2}$ hours of 1 hr. 30 min (a)