When Raj travels with 40 km/hr , he reach 1 hr before and if he travels with…
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When Raj travels with 40 km/hr , he reach 1 hr before and if he travels with 30 km/hr , he reach 1 hour late. Find the distance between two points and the exact time of reaching destination is 10am, then find the speed with which he has to travel ?
- A.
270 km and 30.64 km.hr
- B.
200 km and 36.64 km.hr
- C.
180 km and 26.64 km.hr
- D.
240 km and 34.28 km.hr
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Correct answer: D
Answer: 240 km and 34.2857 km/hr (≈34.29 km/hr)
Let the distance be x km.
The trip at 40 km/hr arrives 1 hour early and at 30 km/hr arrives 1 hour late, so the difference in times is 2 hours: x/30 - x/40 = 2.
Compute the left side: (1/30 - 1/40) = (4 - 3)/120 = 1/120. Thus x/120 = 2, so x = 240 km.
Time taken at 40 km/hr = 240/40 = 6 hours, which is 1 hour less than the scheduled time, so the scheduled time is 7 hours.
Required speed to arrive exactly on time = distance / scheduled time = 240/7 ≈ 34.2857 km/hr (≈34.29 km/hr).
If the destination must be reached at 10:00 AM, the departure time would be 10:00 AM − 7 hours = 3:00 AM.