Q.

After covering a distance of 30 km   with a uniform speed, there is some defect in a train engine and therefore, its speed is reduced to 4 5  of its original speed. Consequently, the train reaches its destination late by 45 min. Had it happened after covering 18 km   more, the trains would have reached 9 min earlier. The speed of train and the distance of journey is


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a

The speed of train is 50 km/hr and the distance of journey is 120km

b

The speed of train is 40 km/hr and the distance of journey is 110km

c

The speed of train is 20 km/hr and the distance of journey is 100km

d

The speed of train is 30 km/hr and the distance of journey is 120km 

answer is D.

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Detailed Solution

Given with a uniform speed train covers 30 km and after some defect in train engine the speed of train is reduced to 4 5  of its original speed.
Distance travel = speed × time
Let, the speed of train be x and distance travel be y, then,
According to the given condition,
30 x + y30 4/5x = y x + 45 60 48 x + y48 4/5x = y x + 36 60 Solving above equations, we get  x=30 and y=120  
Therefore, the speed of the train is 30 km/hr and the distance of journey is 120km.
Hence, option (4) is correct.
 
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After covering a distance of 30 km   with a uniform speed, there is some defect in a train engine and therefore, its speed is reduced to 4 5  of its original speed. Consequently, the train reaches its destination late by 45 min. Had it happened after covering 18 km   more, the trains would have reached 9 min earlier. The speed of train and the distance of journey is