At the end of World War III, the country of Puzzandia has lost many of their planes due to lack of armor. As Puzzandia's plane maker, it is your duty to put armor on the planes. Each plane has been divided into 4 sections; The engine, the fuel tanks, the wings, and the rest of the plane. The only problem is, Puzzandia has only provided you with enough armor to cover 1 section. You are given statistics from the planes that have came back:

Section      Bullet Holes per square foot

Engine       1.12
Fuel Tanks   1.43
Wings        1.89
Other        1.56

Which section of the Plane should you put the armor on, and why?

  • $\begingroup$ Nice post and welcome to the site, Zani Xu. But it is a duplicate, indeed. Hence the VTC. $\endgroup$
    – BmyGuest
    Jun 9, 2018 at 17:28
  • $\begingroup$ Hm, the duplicate does not ask which side of the plane to put the armor, only why? $\endgroup$
    – Jay
    Jun 10, 2018 at 2:00

1 Answer 1


You armour the



The least damage occurred there yet planes were lost.
I.e. the statistics indicate that those planes taking just more than 1.12 bullets in the engine area, they were lost, and could not contribute to a higher number, whereas the wings could almost absorb 2 bullets before being lost. This indicates that it is the engine that needs more protection from bullets than any other area.

This is reminiscent of this story from World War II: https://www.fastcodesign.com/1671172/how-a-story-from-world-war-ii-shapes-facebook-today

  • $\begingroup$ If you reword your reasoning, I might be able to accept your answer. $\endgroup$ Jun 9, 2018 at 15:49
  • $\begingroup$ @ZaniXu - added a bit more explanation, hope that clarifies. $\endgroup$
    – Phylyp
    Jun 9, 2018 at 15:52
  • 1
    $\begingroup$ @ZaniXu - thank you, I only knew this because I had used this very example to illustrate counter-intuitive solutions. $\endgroup$
    – Phylyp
    Jun 9, 2018 at 15:56

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