On 05/06/2015 15:32, Tim Watts wrote:


I had a look back.

For comparison, here is avery uk.d-i-y oritent Uni London Board O-Level
question from 1988:

http://tinypic.com/m/ip8900/3

If you assume there is no change in volume then you can also assume they
aren't making any concrete so the answer to a will be anything you like
unless they are only counting the volume of clippings.


And here's a 1957 Cambridge paper, also O-Level:

http://tinypic.com/m/ip8900/3