A boat travels from point A to B, a distance of 12 km. From A it travels 4 km downstream in 15 minutes and the remaining 8 km upstream to reach B. If the downstream speed is twice as high as the upstream speed, what is the average speed of the boat for the journey from A to B?
Answers
4 km downstream is covered in 15 min. ∴ speed of downstream = 16 km/hr. So speed of upstream = 8km/hr. Total time taken for downstream journey = 15 min (given). Now total time taken for upstream journey = 8/8 = 1 hr = 60 min. Hence total time taken from A to B = 15 + 60 = 75 min. As average speed = Total distance /total time, so average speed from A to B = (12/75)*60 = 48/5 = 9.6kmph.
Answer:
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Step-by-step explanation:
=> 4 km downstream is covered in 15 min.
=> ∴ speed of downstream = 16 km/hr.
=> So speed of upstream = 8km/hr.
=> Total time taken for downstream journey = 15 min (given).
=> Now total time taken for upstream journey = 8/8 = 1 hr = 60 min.
=> Hence total time taken from A to B = 15 + 60 = 75 min.
=> As average speed = Total distance /total time,
=> so average speed from A to B = (12/75)*60 = 48/5 = 9.6kmph.
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