Given:
An athlete who makes [tex]4\dfrac{3}{4}[/tex] laps in 3 mins 45 seconds on a 400m field.
To find:
The speed of the athlete in m/s.
Solution:
We know that,
Distance covered in 1 lap = 400 m
Distance covered in [tex]4\dfrac{3}{4}[/tex] laps = [tex]4\dfrac{3}{4}\times 400[/tex] m
= [tex]\dfrac{19}{4}\times 400[/tex] m
= [tex]1900[/tex] m
We know that,
1 minute = 60 seconds
3 minutes = 180 seconds
3 minutes 45 second = 180 + 45 seconds
= 225 second
The speed of the athlete is:
[tex]Speed=\dfrac{Distance}{Time}[/tex]
[tex]Speed=\dfrac{1900}{225}[/tex]
[tex]Speed\approx 8.44[/tex]
Therefore, the speed of the athlete is about 8.44 m/s.