How Do You Fight a Horse-Sized Duck by William Poundstone

Reviewed by Gerard Healy

A very interesting look at the array of puzzles, odd-ball questions and games thought up by HR departments to help select the best applicants for top-flight jobs. The author is William Poundstone, an American, and while his focus is mainly on the US, many of the job-selection processes he describes would be applicable world-wide.

The title comes from a quirky question along these lines: Would you rather fight one horse-sized duck or 100 duck-sized horses? It is one of those teasers that doesn’t have a “right” answer as such but helps give an interviewer some insight into how you think. You might interpret the question as asking whether you’d rather tackle one big problem or lots of smaller ones (think of the returns desk at a major retailer). Another avenue to explore is to muse on the ability of a duck’s legs to carry all that extra weight and the likelihood it might just collapse onto the ground – thus solving your problem.

In an informative section about the origins of IQ testing and the American Army’s screening tests in WW1, Poundstone mentions Thomas Edison, famed inventor/businessman. Edison, who worked 20 hour days apparently, thought it was important that his employees noticed things. In 1921, he came up with 48 “exceedingly simple” questions to gauge whether someone got a job with his company. Think you’ve got the goods: ready, set, go…

What countries bound France?* What is the speed of sound? Name three powerful poisons. Who wrote Les Miserables? And so on… I don’t know about you but I wouldn’t have passed.

Edison was so well respected in America that his idea of applicant screening in this way took off, even though, as Poundstone points out, there is questionable value in such an approach. What evidence is there that doing well on such a quiz predicts later work performance?

Fast forward to World War 2 and the search for staff at Britain’s code-breaking centre, Bletchley Park. Oxford and Cambridge Universities, from which many applicants were recruited, were already noted for their left-field questions such as: why don’t animals have wheels? Bletchley Park also looked for people with an interest in solving cryptic crossword puzzles as part of the screening process.

Alan Turing, a Cambridge mathematician and their star recruit, helped develop the Bombe, a machine that tackled the German Enigma messages. He later built the Colossus, “considered the first programmable digital computer.”(49). The rise of the computer industry in the 1950s saw firms using logic puzzles to recruit programmers.

Apparently Elon Musk’s (of Tesla and SpaceX fame) favourite interview question was this one: You’re standing on the surface of Earth. You walk one mile south, one mile west and one mile north. You end up exactly where you started. Where are you?

Give up? The classic answer is the North Pole but there’s more than one solution to this. Musk was looking for people who could persist with a problem and think under pressure.

There’s a considerable amount of mathematical reasoning spread throughout this book and Poundstone goes into detail on alternate answers to the Musk question (pp 52-54). Year 12 Maths is one subject that might leave some readers struggling to follow, but you can but admire the explanations. For engineers, this would be child’s play.

Poundstone states that “puzzle-style questions inherit the usual failings of interviews. Evaluations based on them may reflect confirmation bias.” (56) That is, interviewers form a favourable view and then go looking for evidence that backs up that view. Of course, in certain fields, some groups in society rarely get to the interview stage at all.

Take professional musicians, almost all of whom were male until quite recently (the Berlin Philharmonic did not hire a woman until 1982). Some of the reasons given for not hiring women sound ridiculous – playing a horn distorts a pretty face was one example.

One interesting solution to this was the “blind audition” (60). A musician applying for a job performs a set piece behind a screen to a panel, identified only by a number and without speaking. Usually, this is one part of the interview process, but it has seen an increase of female members of American orchestras to around 40% in 2019, from less than 5% in the early 1970s.

What about blind auditions for regular jobs? This has led to the increasing use of psychometric games, which are fast-paced on-screen puzzles and games, as a way to sift through the large numbers of applicants for some jobs. In 2017, Tesla received 200 applicants for each vacancy, hence the need to winnow down the large pool into a more selective group for face-to-face interviews.

I really enjoyed trying to work out many of the puzzles set in this engaging book and would recommend it. If you’re going for a top-level job, it would be very useful indeed.

France is bound by Belgium, Luxembourg, Germany, Switzerland, Italy and Spain.*

William Poundstone was born in 1955 in West Virginia and attended MIT where he studied physics. He has written over a dozen books as well as articles for The New York Times, Harvard Business Review and Harpers. His 2005 book ‘Fortune’s Formula” was Amazon’s No 1 non-fiction title that year and he won the NYSSCPA’s Excellence in Journalism award in 2011. He lives in Los Angeles.


How Do You Fight a Horse-Sized Duck? And other perplexing puzzles from the toughest interviews in the world.


by William Poundstone

Oneworld Publications UK

ISBN: 9780861540075

$34.99 (HB); 320pp


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