There are 51 vans in a showroom which are ready to sell with numbers from \(1\) to 51 marked on each of them. Then answer the following questions.
 
Questions:
 
(I) What is the probability of 5 vans getting sold?  
 
The probability of 5 vans getting sold \(=\) ii
 
(II) What is the probability of 20 vans getting sold?  
 
The probability of 20 vans getting sold \(=\)  ii
 
[Note: Submit all the answers in fraction without solving].