To count the population of a certain type of pigeon, scientists marked 15 of this type of pigeon and then released them. Later, they caught 20 of this type of pigeon in the same spot and noted that 3 of them were marked. Explain how scientists can use this information to predict the total number of this type of pigeon in this area. Be sure to include the best prediction for the total number of this type of pigeons in your answer.