Discussion

In a 200 metres race A beats B by 35 m or 7 seconds. A's time over the course is:

Answer: C

"By 35 m or 7 seconds" means B needs 7 seconds to cover that last 35 m.

\[ v_{B} = \frac{35}{7} = 5 \text{ m/s} \]

\[ t_{B} = \frac{200}{5} = 40 \text{ s} \]

\[ t_{A} = 40 - 7 = 33 \text{ s} \]

The pairing of a distance with a time is what gives the loser's speed, and everything else follows from it.

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