Multiple choice

John and Alex compete in a 500-meter race. John runs at a constant speed of 8 meters per second, while Alex runs at 10 meters per second. To make the race fair, Alex gives John a 50-meter head start. Who wins the race, and how much time does the winner take to finish the race?

  1. John, 60 seconds

  2. Alex, 60 seconds

  3. Alex, 55 seconds

  4. Alex, 50 seconds

  5. John, 55 seconds
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D Correct answer
Explanation

John has a 50m head start, so he runs 450m. Time = 450/8 = 56.25 seconds. Alex runs 500m. Time = 500/10 = 50 seconds. Alex finishes in 50 seconds, which is faster than John's 56.25 seconds.

AI explanation

Alex must cover the full 500-meter distance at 10 meters per second, so by the formula time = distance divided by speed, his time is 500 divided by 10, equaling 50 seconds. In that same 50 seconds, John covers only 8 times 50, or 400 meters; since John started 50 meters ahead, he reaches only the 450-meter mark when Alex finishes. Alex finishes the race first, and the winner takes 50 seconds to complete the race.

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