Badri and Vasu are running at the same speed of 12 kms/hr. However, Badri…
2018
Badri and Vasu are running at the same speed of 12 kms/hr. However, Badri started an hour earlier than Vasu. The distance between source and destination is 200 kms. After Vasu has covered 40 kms, he decides to increase his speed so that both of them reach the destination on time. By how much should Vasu increase his speed (in kms/hr)?
- A.
1.04
- B.
0.89
- C.
1.1
- D.
0.97
Attempted by 3 students.
Show answer & explanation
Correct answer: D
To find out how much Vasu must increase his speed, we need to calculate the time constraints for both runners to reach the 200 km destination.
Step-by-Step Analysis
Calculate Badri's total travel time:
Badri travels 200 km at 12 km/hr.
Time = Distance / Speed = 200 / 12 = 50/3 hours (approx. 16.67 hours).
Calculate Vasu's remaining time:
Badri started 1 hour earlier, so Vasu has 1 hour less to complete the journey.
Total time available for Vasu = (50/3) - 1 = 47/3 hours.
Analyze Vasu's journey:
Vasu has already covered 40 km at 12 km/hr.
Time taken for the first 40 km = 40 / 12 = 10/3 hours.
Remaining distance for Vasu = 200 - 40 = 160 km.
Remaining time for Vasu = (47/3) - (10/3) = 37/3 hours.
Calculate the required speed for the remaining distance:
Required Speed = Remaining Distance / Remaining Time = 160 / (37/3) = 480/37 km/hr.
Calculate the required increase:
Original speed = 12 km/hr = 444/37 km/hr.
Increase = (480/37) - (444/37) = 36/37 km/hr.
36 / 37 is approximately 0.9729 km/hr.