Multiple choice

A man swims 12 km downstream and 10 km upstream. If he takes 2 hours each time, what is the speed of the stream?

  1. 1 km/hr

  2. 0.5 km/hr

  3. 1.5 km/hr

  4. 0.7 km/hr

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Downstream speed = 12 km / 2 hr = 6 km/hr. Upstream speed = 10 km / 2 hr = 5 km/hr. Stream speed = (Downstream - Upstream) / 2 = (6 - 5) / 2 = 0.5 km/hr.

AI explanation

Using the formula Speed equals Distance divided by Time, the downstream speed is 12 divided by 2, which equals 6 km/hr. The upstream speed is 10 divided by 2, which equals 5 km/hr. Using the formula for the speed of the stream, which is half the difference of downstream and upstream speeds, we calculate (6 minus 5) divided by 2. The speed of the stream is 0.5 km/hr.