To travel 672 km, an Express train takes 14
hours more than Rajdhani. If however, the speed of the
Express train is doubled, it takes 8 hours less than
Rajdhani. The speed of Rajdhani is
1). 30.5 km/hr
2). 14.3 km/hr
3). 38.7 km/hr
4). 22.4 km/hr
Let time taken by Rajdhani be y hours
Let the speed of Express train be x km/hr
Time taken by Express train $\large = \frac{672}{x}$
$ \large \frac{672}{x} = y + 14 $- - - - - (1)
New speed of Express train be $2x$ km/hr
Time taken by Express train $ \large = \frac{672}{2x}$
$\large \frac{672}{2x} = y – 8$ - - - - - - (2)
From (1) and (2) we get $ \large x = 15.27$ km/hr and $\large y = 30$ hr
Speed of Rajdhani $ \large= \frac{672}{30} = 22.4$ km/hr