By changing the position of the fewest possible
number of the ten ducks, arrange them so there
will be five rows of four in each row.
 

The subject of this puzzle is a fimiliar one to residents in
the vicinity of Buzzard's Bay and introduces one of the many
problems which have doubtless been noticed by all who revel
in the pleasures of duck shooting.

There are a thousand and one problems connected with the sport,
any one of which would be worthy of consideration, but with
which our puzzlists are doubtless more familiar than myself,
so I only refer to one little proposition which may be pecu-
liarly characteristic of my style of duck shooting.  Of course
it is a great feat to get more than one duck at a single shot.
As that can only be done by getting several of then in a line,
it set me to studying the principle upon which Buzzard Bay
ducks line up, and I may have hit upon something which my
uniform lack of skill as a marksman enabled me to discover.

I noticed that the birds invariably approached in two rows,
with a corporal bird, so to speak, on each side in charge of
either line, so that, as shown, one could figure out three
lines of four-in-a-row.  Now just as soon as I got a line on
four of these birds I would blaze away in the hope of getting
several birds with one shot.  I could readily have killed one
bird or possibly two, but my ambition to get four or none led
to my making the following interesting discovery.  As soon as
the smoke cleared away, so that I could open my eyes, I would
find that the ten birds had reversed their direction, to reor-
ganize somewhere back in the swamps.  What I particularly
noticed, however, was that while they came in the three four-
in-a-row form as shown, they invariably scotted away in the
shape of five rows, with four-in-a row.  Just how they made
the change I never could see, on account of the smoke and
confusion, but I noticed that the fewest possible number of
birds had changed their positions, so it will afford me special
pleasure to give credit to any lucky duck who will solve this
little problem for me correctly.

The picture shows ten ducks advancing in three rows of four-
in-line.  Now reorganize them so there will be five rows of
four-in-line, simply by changing the position of the fewest
possible number of ducks.  Incidently, it will also show how
many ducks Grover bags out of the flock.

The problem can be worked out practically by placing small
counters upon the ducks in the picture and moving them
around until you get five rows of four-in-a-row.

Click below to read Sam Loyd's solution.