1. 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
Write Comment
Comments
By: anil on 05 May 2019 02.15 am
Let speed of Rajdhani train = $$x$$ km/hr and Express train = $$y$$ km/hr Using, time = distance/speed Acc. to ques, => $$frac{660}{y} - frac{660}{x} = 10$$ => $$frac{1}{y} - frac{1}{x} = frac{10}{660} = frac{1}{66}$$ ----------------(i) If speed of express train is doubled = $$2y$$ km/hr => $$frac{660}{x} - frac{660}{2y} = 7$$ => $$frac{1}{x} - frac{1}{2y} = frac{7}{660}$$ ----------------(ii) Adding equations (i) and (ii), we get : => $$frac{1}{y} - frac{1}{2y} = frac{1}{66} + frac{7}{660}$$ => $$frac{1}{2y} = frac{17}{660}$$ => $$y = frac{330}{17}$$ km/hr $$ herefore$$ Speed of Rajdhani = $$frac{1}{x} = frac{17}{330} - frac{1}{66}$$ => $$frac{1}{x} = frac{17-5}{330} = frac{12}{330} = frac{2}{55}$$ => $$x = 27.5$$ km/hr => Ans - (D)
Terms And Service:We do not guarantee the accuracy of available data ..We Provide Information On Public Data.. Please consult an expert before using this data for commercial or personal use