The Guardian's puzzle columnist published the solutions to four engineering-themed brainteasers set earlier in the day, each illustrating how real-world design involves trade-offs rather than perfect solutions. The puzzles, adapted from Alex Davies's book *How to Keep a Plane in the Sky*, covered cranberry sorting, child-resistant medicine caps, the Golden Gate Bridge's handrail redesign, and how engineers safely pressure-tested the de Havilland Comet, the world's first commercial jet.

Answers included tilting a sorting board so bouncy (good) cranberries land on a conveyor belt while soft (bad) ones fall away, and setting medicine bottle caps to resist only 85% of under-fives so elderly or arthritic users aren't locked out entirely. The 2020 Golden Gate Bridge handrail redesign, meant to reduce wind resistance, instead increased wind speeds for cyclists and caused the bridge to emit a harmonica-like whistle. Finally, in the 1950s de Havilland tested the Comet's fuselage limits by submerging it in a giant water tank at Farnborough and pressurising it with water rather than air, allowing engineers to find the point of structural failure safely rather than risk an explosive mid-air disintegration.