A and B start running on a circular race track whose length is 3240 m. A and B start from the same point and at the same time, but in opposite directions. If A runs at a speed of 10 m/s and they cross each other 3 minutes after they start running, then what is B's speed (in m/s)?
Answer
The correct answer is C: 8. Combined speed = 3240 / (3×60) = 18 m/s. Since A's speed is 10 m/s, B's speed = 18 − 10 = 8 m/s.