A man rows upstream in still water at 3 km/h and back to the same place at 5 km/h; he takes 48 minutes altogether. How far upstream did he go?
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Given:
- Speed while upstream = 3 km/h
- Speed while downstream = 5 km/h
- Time taken = 48 minute = 0.8 hours
To find:
- Distance travelled by man in upstream?
Solution:
⌬ Let distance travelled by man in upstream be x km.
Therefore,
We know that,
Speed = Distance/Time
∴ Time = Distance/Speed
So,
★ According to the Question:
→ Time taken in upstream + Time taken in downstream = Total time
→ x/3 + x/5 = 0.8
→ (5x + 3x)/15 = 0.8
→ 8x/15 = 0.8
→ 8x = 0.8 × 15
→ 8x = 12
→ x = 12/8
→ x = 3/2
→ x = 1.5 km
∴ Hence, Distance travelled by man is 1.5 km upstream.
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