Multiple choice

A boatman rows $1\ km$ in $5$ min along the stream and $6\ km$ in $1\ h$ against the stream. The speed of the stream is

  1. $3\ km/h$
  2. $6\ km/h$
  3. $10\ km/h$
  4. $12\ km/h$
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A Correct answer
Explanation

Speed downstream = 1 km / (5/60) h = 12 km/h. Speed upstream = 6 km / 1 h = 6 km/h. Speed of stream = (Downstream - Upstream) / 2 = (12 - 6) / 2 = 3 km/h.

AI explanation

Rowing 1 km in 5 minutes along the stream gives a downstream speed of 1 divided by (5/60), which equals 12 km/h. Rowing 6 km in 1 hour against the stream gives an upstream speed of 6 km/h. Using the stream speed formula, half of the difference between the downstream and upstream speeds, the speed of the stream is (12 - 6)/2 = 3 km/h.

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