Multiple choice

If a boat goes 100 km downstream in 10 hours and 75 km upstream in 15 hours, then the speed of the stream is

  1. 2 km./hr.

  2. 2.5 km./hr.

  3. 3 km./hr.

  4. 3.5 km./hr.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Downstream speed = 100/10 = 10 km/hr (boat + stream). Upstream speed = 75/15 = 5 km/hr (boat - stream). Stream speed = (10 - 5)/2 = 2.5 km/hr. This is derived from the standard formula: if downstream speed is D and upstream speed is U, then stream speed = (D - U)/2.

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