Version A:

1:  1 3 5 7
2:  5 3 10 2
3:  11
4:  gon 15
5:  123123456

 6.  7.  8.  9. 10. 11. 12. 13. 14. 15. 
 C   A   C   A   D   A   B   C   D   C

These are possible answers:

16.

class Book:
    def __init__(self, title, author, checkedOut):
        self.__title = title
        self.__author = author
        self.__isOut = checkedOut
    
    def __str__(self):
        status = "checked out" if self.__isOut else "available"
        return self.__title + " by " + self.__author + " is " + status

    def getTitle(self):
        return self.__title

    def getAuthor(self):
        return self.__author

    def checkOutBook(self):
        self.__isOut = True

    def returnBook(self):
        self.__isOut = False


17.

def sumAndAveragePositives():
    count = 0
    sum = 0
    while True:
        num = float(input("Enter a number: "))
        if num == 0.0:
            break
        elif num < 0:
            print("Number must be positive.")
        else:
            sum += num
            count += 1
    print("Sum:", sum)
    avg = (0.0 if count == 0.0 else sum / count)
    print("Average:", avg)