Multiple choice

The speed of boat in still water is $10$ km per hr. If the boat goes $37.5$ km upstream in $5$ hours, find the speed of the stream.

  1. $2.5$ km/hr
  2. $1.5$ km/hr
  3. $3.4$ km/hr
  4. $5.4$ km/hr
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A Correct answer
Explanation

Upstream speed = distance / time = 37.5 / 5 = 7.5 km/hr. Upstream speed = boat speed - stream speed. 7.5 = 10 - stream speed, so stream speed = 2.5 km/hr.

AI explanation

The upstream speed is the distance divided by the time, giving 37.5 km divided by 5 hours, which equals 7.5 km/hr. Using the formula for upstream speed, where upstream speed equals the boat speed in still water minus the stream speed, we write 7.5 = 10 minus the stream speed. Solving this gives the stream speed as 2.5 km/hr.

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