Question is incomplete as number of trials isn't given. We'll use an hypothetical value to make x plain the situation 
Answer:
Kindly check explanation 
Explanation:
Given that the number of trials = x
If the number of tines the ball was hit out if 'x' trials = 3 
The ratio of the number of hits to the number of trials is written as :
Number of hits : Number of trials
3 : x
Just put the exact value of x in the equation above and if possible, reduce to simplest form.