Arat in a skinner box receives a food pellet every ten times the bar is pressed. the rat is on a schedule of reinforcement.

Fixed ratio

Explanation:

The Fixed ratio schedule is used in ope-rant conditioning. Ope-rant conditioning is work on the relationship of response and stimulus due to that the behavior of a subject has been changed.

As the name indicated the reinforcement is being given after a fixed ratio for example after every ten times the reinforcement is provided to the rat in the box. So the rat can learn the behavior.

In this type of reinforcement, the schedule will remain constant. If the reinforcement is not provided after a fifth, tenth or any fixed number then it won't be a fixed ratio.  

can you explain it better