dreambeliever wrote:
A train met with an accident 60km away from station A. It completed the remaining journey at 5/6th of the original speed and reached station B 1hr 12mins late. Had the accident taken place 60km further, it would have been only 1hr late. what was the original speed of the train?
a. 60 km/hr
b. 55 km/hr
c. 65 km/hr
d. 70 km/hr
e. 48 km/hr
The logical approach here is this:
The accident took place 60 km from A. The train was delayed by 1hr 12 min. If it had instead taken place 120 km from A, it would have been only 1 hr late. What does this 12 min gap in time signify? It is the delay caused by reducing the speed by (1/6)th over a distance of 60 km. The ratio of the speed over this 60 km stretch is 5:6 (speed reduced by a sixth : original speed)
Time taken 6:5 (Time taken with reduced speed : original time taken)
We know this difference of 1 in time taken is given by 12 min. So original time taken is 12*5 = 60 min = 1 hr
Time taken is 1 hr to cover a distance of 60 km so speed = 60 km/hr
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Karishma
Veritas Prep GMAT Instructor
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