Answer:
The time-interval of the collision is 

Step-by-step explanation:
As given the force is equal to the rate of change of momentum. Mathemticaly this is:

We can rearrange this equation to solve for 
 which gives
 which gives 
 
 
 
which is our answer.
In words this means the time interval is equal to the momentum change in that interval divided by the force applied that caused this momentum change.