Rory Sutherland

# The case for maths to 18

Recently Chinese 11-year-olds faced the following question in a maths exam. ‘If a ship has 26 sheep and ten goats on board, how old is the ship’s captain?’ Chinese social media lit up with parents furious at their little emperors being asked a question they could not answer.

The BBC did find one Weibo user who had devised a plausible solution. ‘The total weight of 26 sheep and ten goats is 7,700kg. In China, if you’re controlling a ship with over 5,000kg of cargo you need to have possessed a boat licence for five years. The minimum age for getting the licence is 23, ergo the captain is at least 28.’ But if this were the desired answer, it would seem to require a freakish childhood obsession with nautical regulations, and, as a Welshman, I can’t help pointing out that the solution has been obtained only by assuming a cargo of remarkably chubby livestock.

Thankfully some internet detectives went to work on the question, among them Presh Talwalkar of the MindYourDecisions YouTube channel. It turns out this puzzle has its origins in France, in a letter from Gustave Flaubert to his sister in 1841. Then, in 1979, a shorter version, identical to the later Chinese question, was posed verbatim to French schoolchildren as a psychological experiment. The aim was to find out if the assumed certainty implicit in maths tests would lead people to give definitive answers at the expense of critical thinking. It did. Around three quarters of pupils answered ‘36’ (i.e. 26 plus ten) or else contrived some other number. Fewer than a quarter wrote ‘not enough information’. Similar results emerged in Germany and Switzerland.

‘Trick’ questions of this kind are commonly used in educational studies.

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Rory Sutherland