Multiple choice

Alex notices a yacht that has already sailed 60 nautical miles out of a 100-nautical-mile course. Initially, the yacht is cruising at a speed of 8 knots in calm waters. Suddenly, it catches a favorable current of 2 knots, pushing it in the same direction. If t represents the time taken in hours to cover the remaining distance, which equation below best describes this scenario? [1 knot = 1 nautical mile per hour]

  1. 60 = 40 + 8t

  2. 100 = 60 + 10t

  3. 100 = 40 + 9.2t

  4. 160 = 11.5t + 40
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Remaining distance = 100 - 60 = 40 nautical miles. Speed = 8 + 2 = 10 knots. Time t = distance / speed, so 40 = 10t. The total distance 100 is equal to the distance already covered (60) plus the distance covered in time t (10t). Thus, 100 = 60 + 10t.

AI explanation

The yacht's total journey is 100 nautical miles, and it has already covered 60 nautical miles. With the favorable current, the new speed is 8 plus 2, equaling 10 knots, or 10 nautical miles per hour. Therefore, the equation for the remaining distance is 100 = 60 + 10t.

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