A journey takes 4 hours 30 minutes at a speed of 60 km/hr. If the speed is 15 m/s, then the journey will take :

September 1, 2016 September 1, 2016

A journey takes 4 hours 30 minutes at a speed of 60 km/hr. If the speed is 15 m/s, then the journey will take :
[A]5 hours
[B]5 hours 30 minutes
[C]6 hours
[D]6 hours 25 minutes

5 hours
$60\ km/hr = 60\times \frac{5}{18}\ m/s = \frac{50}{3}\ m/s$
$\therefore\ Speed \propto \frac{1}{Time}$
$=> S_{1}\times T_{1} = S_{2}\times T_{2}$
$=> \frac{50}{3}\times \frac{9}{2} = 15\times T_{2}$
$=> 75 = 15\times T_{2}$
$=> T_{2} = \frac{75}{15} = 5\ hours$
Hence option [A] is correct answer.