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A steamer goes downstream from one port to another in 4 hours. It covers the same distance upstream in 5 hours. If the speed of the stream be 2 km/hr, find the distance between the two ports.
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- 60 km.
- 45 km.
- 80 km.
- 65 km.
Correct Option: C
Let the speed of steamer in still water = x kmph
∴ Rate downstream = (x + 2) kmph
Rate upstream = (x – 2) kmph
Obviously, distance covered downstream and upstream are equal
⇒ 4 (x + 2) = 5 (x – 2)
⇒ 4x + 8 = 5x – 10
⇒ 5x – 4x = 10 + 8 ⇒ x = 18
∴ Rate downstream
= 18 + 2 = 20 kmph
Therefore, the required distance
= Speed downstream × Time
= 20 × 4 = 80 km.
