a puxxle

Neil Fernandez primeness at borve.demon.co.uk
Sun Apr 16 11:54:11 CEST 2006

In message <200604141440.k3EEdxJ00966 at zen.crypt.org>, hv at crypt.org

>"N. J. A. Sloane" <njas at research.att.com> wrote:

>:%S A117713 1,3,8,18,__,89,189
>:%N A117713 This sequence was a question on a civil service test a friend of 
>mine took. They had to fill in the blank number. Is there an answer to this??.

I think there are two main possibilities:

1) the question is supposed to get candidates a) to think out of the
box, and b) to deal with not getting a 'proper' answer. Full marks might
go to someone who responded by saying 'I couldn't find an answer, but if
89 and 189 were changed to 88 and 188 it would be the coin sequence'. In
the context of a civil service exam it is not sensible to spend a huge
amount of time looking for a (contrived) answer based on extensive
arithmetical investigation.

Reason: they do ask such questions, to test the brightest candidates.
E.g. they have asked candidates for the UK foreign service to propose a
solution to the Israeli/Palestinian conflict. High marks go to those who
state the opinion that there is no solution in reach. I.e. who say 'I
don't know' in an intelligent way. Coming up with an 'ingenious' plan
would get a low mark. In this scenario, filling in 38, 39, or 40 in
answer to the sequence question would also get a low mark, or no mark.

I would like to know whether it was a multiple choice test with answer
sheets read by machine, or whether it was clear that making an
intelligent comment would reach the examiners' attention. If the latter,
then I think this is the strongest possibility.

2) the last two numbers were actually 88 and 188, and Louis's friend
misremembered them, or they were misprinted, or (less likely) the
examiner made a mistake, and the intended sequence was to do with
British coinage.

(Reason: UK civil service exam questions are graded in order of
difficulty, and this sort of question could certainly get on the list)


Neil Fernandez

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