At the 2008 Summer Olympics in Beijing, China, Usain Bolt (Jamaica) set a new Olympic and world record in the 100-m dash with a time of 9.69 sec. If this pace could be maintained for an entire 26-mi marathon, what would his time be? How would this time compare to the fastest time for a marathon, which is 2 hr, 3 min, 23 sec, set in 2013? (Hint: 1 m≈3.281 1 m almost equal to , 3.281 ft.) (Source: Sports Illustrated Almanac.)

Respuesta :

Answer:

  1 h 7 min 34 sec as compared to 2 h 3 min 23 sec.

Step-by-step explanation:

Since an official marathon is a little longer than 26 miles, we assume this is about conversion factors, not about time.

  [tex]26\,\text{mi}\cdot\dfrac{5280\,\text{ft}}{1\,\text{mi}}\cdot\dfrac{1\,\text{m}}{3.281\,\text{ft}}\cdot\dfrac{9.69\,\text{s}}{100\,\text{m}}=\dfrac{26\cdot 5280\cdot 9.69}{3.281\cdot 100}\,\text{s}\\\\=4054\,\text{s}=1\,\text{hr}\ 7\,\text{min}\ 34\,\text{s}[/tex]

This "sprint speed" time is about 45% less than the fastest time for a marathon.

_____

1 hour = 3600 seconds

1 minute = 60 seconds

_____

Comment on the problem numbers

A marathon is officially 42,195 meters in length. At that length, the "sprint speed" time would be 4088.7 seconds, about 1 hr 8 min 8.7 sec.

26 miles with the given conversion factor results in a distance about 354 meters, or 34.3 seconds, shorter.