Answer:
th part of the field is covered in the second sprint.
Step-by-step explanation:
A football player is running the length of a 100 yard long football field.
Let player sprints x yards with the speed = 2 yards per second.
So time taken to cover x yards player will take time =
seconds
Now rest distance (100 - x) yards when covered with the speed of 4 yards per second, so time taken to cover this distance = 
=
seconds
Now total time taken by the player can be represented by the equation

Now we can solve this equation for the value of x.

x + 100 = 40×4
x + 100 = 160
x = 160 - 100 = 60 yards
And length of the second part will be = 100 - 60 = 40 yards
Now the fraction of the field covered by the player in second sprint will be
= 
=
or 40%
Therefore,
th part of the field was covered in second sprint.