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Sharing Equally ... Is it Possible?
Sharing Equally...is it possible?
Tim Bateman
I was delighted to see, in Equals Vol. 5 No.2, p. 9, a set of seven
possible answers to a division problem in which the differences in answer
depended on the context of the problem. As the following explanations show, the
context is crucial. The problem, you may remember, was sharing 23 equally
between 6. The analysis below may well give those who ?can do? mathematics some
understanding of those who ?can?t?. It may be connected to the difficulty in
abstracting the `correct' answer of 3. 833333..., or 3 5/6, from the numerical
problem of 23 shared equally between 6.1.
Example 1 was: 23 oranges shared equally between 6 people How many oranges
does each person get? The ?answer? given was 3 oranges and 5/6 of an orange.
However, how do you divide an orange exactly into sixths? I
haven?t found one, yet, with six segments; 8, 9, and 10 segments, yes, but not
6. (and even then the segments would have to be of equal size or mass). You
could, perhaps, divide the 5 remaining oranges by weight, but then some people
involved might get a higher proportion of peel than others, and hence it would
not be an equal distribution. Those involved might agree to squeeze all 23
oranges and share the resultant juice and pulp by volume and mass; but I doubt
that this scenario was what Mr. Vertes was thinking of at the time. Within
this mathematical solution we have also assumed that the oranges were all the
same size, shape, and texture. Is this reasonable? Do we always take the first 3
oranges on display, or does the one at the back look sweeter?
Example 2: 23 people go in cars. Each car can take at most 6 people. How
many cars are needed for the group? The simplistic answer is 4, yet we
have assumed that the people are about the same size. However, if 2 or more of
them are over 130 kgs, the answer might have to be 5 or more. We have also
assumed no personality or creed difficulties. In some areas of the world a woman
would not sit next to a man, or a person of one faith might refuse to sit with
one or more of another faith.
Example 3: 23 paper clips are shared amongst 6 people. How are the paper
clips shared? The answer 3 remainder 5 is obviously ?correct?. We
probably have identical paper clips, and we have 5 spares. But why should such a
problem as this arise in the first place? Perhaps the six people have been set a
task which involves the use of 3 paper clips each? and the other 5 are also
needed by the group of 6? Are we to make sure that they all receive them at the
same time? and, if not, we will, to some degree, not have shared them out
equally. (Possible task for the 6 people each person makes a 3 link chain. When
all 6 have been made they join them into one long chain using the remaining 5.)
But then the question should have been, ?How many paper clips do you need
to...??.
Examples 4 and 5: those of sharing winnings and sharing debts, are
very good examples of real life mathematics, showing us how ?correct? answers
can be manipulated by those who have the money to begin with. In the case of
sharing winnings of £23 equally between 6 people, they each gain £3.83. However
6 lots of £3.83 amount to £22.98, and so they have a collective loss of 2 pence.
When 6 people have to share a bill of £23 pounds, they are each charged £3.84.
Again they suffer a collective loss, this time of 4 pence, as 6 lots of £3.84 is
£23. 04. It is true that the people involved could makes arrangements amongst
themselves if they shared the same bills on a regular basis. If two of them
agreed to paid £3.84 on the first occasion whilst the others paid £3.83 pounds,
and the ?pair? who paid the larger amount was rotated, we could have created a
way of sharing the bill ?equally?.
However, it is unlikely, to say the least, that we could arrange a similar
set of circumstances to assist us in sharing the winnings ?equally?, as winnings
do not fall into the category of regular events.
Example 6: 23 full books of stamps, and an offer that allows 6 books to be
exchanged for a CD. How many CDs would you get? Here, obviously, you
would get 3 CDs ( providing you arranged that the exchange took place before the
closing date specified in the offer, that they had not already run out of those
CDs on offer ? and that the offer was not a bogus one); but what would you do
with the other 5?
a) You could contact the company involved , and hope
that they would accept 5 instead of 6 for the 4th
CD. b) You could ask them to put you in touch with
others who also had `spares'. c) You could contact a
radio station and ask them to publish your
dilemma. Or, d) as I suspect would happen in many,
if not most, cases, you could throw them away.
In these circumstances the equality of the sharing depends on the astuteness
and perseverance of the people to whom the offer might be made.
Example 7: 23 is divided by 6, using a calculator. What is the
answer? Here, providing the calculator is used correctly, the answer is
guaranteed, and this will, I?m sure make the Pure Mathematicians happy. However,
as it can?t give the correct answer in the other 6 practical questions, how
accurate, or indeed useful, is it?
Happy mathematical thinking!
Queensmill School, Fulham
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Equals Volume 6 Number
2 (Spring 2000) Page 6 |
© The Mathematical Association 2000
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