It looks rather like the old Imperial pint measures ,with drams fluid ounces and minims . There were 20 fluid ounces in a pint which is the 9600 divided by 480 . The minim , as the name implies was the smallest quantity and I suspect there were 9600 of these (barely a drop) to the pint.
4planks - it's about time you knew that the quiz setter for GBQ takes a very dim view of people asking for help on this site, especially when they don't even confess that it's from his quiz.