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'Rabbits in the Pen' printed from https://nrich.maths.org/
We had a very large number of solutions
sent - many of them were particularly pleasing as they
included really good explanations as to how
you were thinking. This is something we do wish to
encourage.
As well as individual solutions coming in
there were quite a number from groups of children at Oxgangs,
Hotwells, St. Joseph's and Gateway schools. Thank you to the staff
who gave the pupils opportunities to send in solutions. Here is a
solution that came from Amanda and Paula.
Solution to the first pen-
First we started with trial and error to find out how many brown
floppies
there would be. Then we found out that one wouldn't work so we
tried two.
So if there were two brown floppies then there has to be two
brown
ordinaries too. Then we wrote that and charted down the rest of the
categories like this-
Brown flop: 2
Brown ordinary: 2
Black flop : ?
Black ordinary: ?
White flop: ?
White ordinary: ?
After that we tried to find out what the white and black were.. So
we knew
that there are three times as many blacks as whites. So if we put
one next
to the white flop then three next to the black ordinary like
this-
Brown flop: 2
Brown ordinary: 2
Black flop: ?
Black ordinary: 3
White flop: 1
White ordinary: ?
And we knew that it couldn't be black flop because if it was then
there
are three with floppy ears that wouldn't work. And then we put in
zeros
next to the empty ones like this-
Brown flop: 2
Brown ordinary: 2
Black flop: 0
Black ordinary: 3
White flop: 1
White ordinary: 0
And then we checked it and it worked.
Solution to the second pen-
First we did trial and error to try and find out how many floppy
browns
there are. Then we started with one and we knew that couldn't be
right
because brown ordinary has to be half of brown flop. There can only
be one
ordinary so brown flop definitely had to be two. We put zeros next
to all
the ordinaries because there can only be one ordinary and that is
brown. We
wrote it out like this-
Brown flop: 2
Brown ordinary: 1
Black flop; ?
Black ordinary: 0
Grey flop: ?
Grey ordinary: 0
Then to find out what black flop was we added up both the browns
and it
equaled three. We did that because there is the same number as
blacks as
browns. We added it in like this-
Brown flop: 2
Brown ordinary: 1
Black flop: 3
Black ordinary: 0
Grey flop: ?
Grey ordinary: 0
So now all we need to work out is grey flop. And we knew that there
are
the same number as floppy browns as floppy greys. Floppy brown is
two so
grey flop is also two.So we put it like this-
Brown flop: 2
Brown ordinary: 1
Black flop: 3
Black ordinary: 0
Grey flop: 2
Grey ordinary: 0
Then we checked it and we found out it all worked out.