Multiple choice

It takes a boat 2 hours to travel 24 miles downstream and 3 hours to travel 18 miles upstream. If the speed of the boat is x mph and the speed of the current is y mph, then what is the speed of the boat in still water and how fast is the current?

  1. 3 mph, 9 mph

  2. 9 mph, 3 mph

  3. 7 mph, 2 mph

  4. 8 mph, 5 mph
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Downstream speed (x + y) = 24/2 = 12 mph. Upstream speed (x - y) = 18/3 = 6 mph. Solving the system: 2x = 18 implies x = 9, and 9 + y = 12 implies y = 3.

AI explanation

The downstream speed is 24 miles / 2 hr = 12 mph and the upstream speed is 18 miles / 3 hr = 6 mph. The speed of the boat in still water is half the sum of these speeds, meaning (12 + 6) / 2 = 9 mph. The speed of the current is half the difference, meaning (12 - 6) / 2 = 3 mph. The result is 9 mph for the boat and 3 mph for the current.

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