Answer:
The mass of sprinter is 65 kg.
Explanation:
Force is defined as the push or pull on an object with some mass that causes change in its velocity.
It is also defined as the mass multiplied by the acceleration of the object.
Mathematically,

where,
F = force exerted on starting blocks = 100 N
m = mass of the sprinter = ?
a = acceleration of the sprinter = 
Putting values in above equation, we get:

Hence, the mass of sprinter is 65 kg.