Multiple choice

John covers 22 km upstream in 660 minutes and 30 km downstream in 360 minutes. What is the rate of current?

  1. 1 km/hr

  2. 1.5 km/hr

  3. 3 km/hr

  4. 4.5 km/hr

  5. 5 km/hr
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Upstream speed = 22 km / (660/60) hr = 2 km/hr. Downstream speed = 30 km / (360/60) hr = 5 km/hr. Current rate = (Downstream - Upstream) / 2 = (5 - 2) / 2 = 1.5 km/hr.

AI explanation

Convert the travel times to hours, giving 660 minutes as 11 hours and 360 minutes as 6 hours. The upstream speed is 22 km divided by 11 hours, equaling 2 km/hr, and the downstream speed is 30 km divided by 6 hours, equaling 5 km/hr. The rate of the current is half the difference of the downstream and upstream speeds, calculating to 1.5 km/hr.

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