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The person is called a Marshal.
It is debatable about what an average person is. An average swimmer can swim 2640 yards in about 30-50 minutes. It just depends if they are a swimmer.
Most people (that can swim) can swim 400 yards. The speed of how they do that although varies.
0.5 mile = 880 yards - whether you swim or walk or run is irrelevant.
It is when you swim competitively. You take part in races. You swim to go fast.
0.114 miles
400 meters = 437.45 yards
to swim 800 meters in a 25 meter poll, you must swim 32 lengths, but to swim 800 YARDS, you only have to swim 29.26 lengths (so you should just swim 30 lenghts)
A lap is technically 2 lengths. And every 2 lengths in 50 yards. Therefore, you would have to swim 10 lengths (or 5 laps) to complete 250 yards.
1/3 mile = 586.67 yards.
You will need to swim 15 lengths and you will end up swimming 410 yards.
it takes 50 seconds.