To travel 660 km, an Express train takes 10 hours more than Rajdhani. If however, the speed of the Express train is doubled, it takes 7 hou… — Answer & Discussion

To travel 660 km, an Express train takes 10 hours more than Rajdhani. If however, the speed of the Express train is doubled, it takes 7 hours less than Rajdhani. The speed of Rajdhani is

A38.8 km/hr
B16.2 km/hr
C50.1 km/hr
D27.5 km/hr

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Discussion 1

CCommunity18 Jun 2019

Let time taken by Rajdhani be y hrs

Let the speed of Express train be x km/hr

Time taken by Express train = 660/x

660/x = y + 10 ----(1)

New speed of Express train be 2x km/hr

Time taken by Express train = 2x/660

660/2x = y - 7 ----(2)

From (1) and (2) we get x = (660/34) km/hr and y = 24 hr

Speed of Rajdhani = 660/24 = 27.5 km/hr