Fifty people own 4,000 books. what's the ratio of people to books?

To determine the ratio (r) of people to books, simply divide the number of people (P) to the number of books (B). This is shown in the equation below.
 
                                             r = P / B 

Substituting the given values,
 
                                       r = 50 people / 4,000 books
                                           r = 1 / 80

Thus, the ratio of people to books is 1:80.