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The Delhi Express runs @ 144 kilometers per hours and it reaches destination 20 minute ahead of schedule. If it averages 100 km/hour, it reaches 24 minute behind schedule. What is the average speed it
- A250
- B240
- C230
- D245
Correct answer: B
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0
CCommunity
240
NA
NA
0
CCommunity
Solution:
Let 'D' be the distance and 'S' be the speed taken by the train to reach the destination on time.
So, the time taken to reach the destination on schedule = D/S hour
Given: With a speed of 144 km/hr, the train reaches 20 minutes ahead of schedule so,
D/144 = D/S - 1/3 ( Since 20 min = 1/3 hr )
Next, with a speed of 100 km/hr ,the train reaches 24 minutes behind the schedule so,
D/100 = D/S + 2/5 ( Since 24 min = 2/5 hr )
D/100 = D/144 + 1/3 + 2/5
D/100 - D/144 = 11/15
44D/14400 = 11/15
4D /960 = 1
D = 960/4
D = 240
So, the distance of the destination is 240km
The correct option is B). 240
Let 'D' be the distance and 'S' be the speed taken by the train to reach the destination on time.
So, the time taken to reach the destination on schedule = D/S hour
Given: With a speed of 144 km/hr, the train reaches 20 minutes ahead of schedule so,
D/144 = D/S - 1/3 ( Since 20 min = 1/3 hr )
Next, with a speed of 100 km/hr ,the train reaches 24 minutes behind the schedule so,
D/100 = D/S + 2/5 ( Since 24 min = 2/5 hr )
D/100 = D/144 + 1/3 + 2/5
D/100 - D/144 = 11/15
44D/14400 = 11/15
4D /960 = 1
D = 960/4
D = 240
So, the distance of the destination is 240km
The correct option is B). 240