Note to recruiters

Note to recruiters: We are quite aware that recruiters, interviewers, VCs and other professionals generally perform a Google Search before they interview someone, take a pitch from someone, et cetera. Please keep in mind that not everything put on the Internet must align directly to one's future career and/or one's future product portfolio. Sometimes, people do put things on the Internet just because. Just because. It may be out of their personal interests, which may have nothing to do with their professional interests. Or it may be for some other reason. Recruiters seem to have this wrong-headed notion that if somebody is not signalling their interests in a certain area online, then that means that they are not interested in that area at all. It is worth pointing out that economics pretty much underlies the areas of marketing, strategy, operations and finance. And this blog is about economics. With metta, let us. by all means, be reflective about this whole business of business. Also, see our post on "The Multi-faceted Identity Problem".

Thursday, April 12, 2012

The two wires puzzle a.k.a. the Chandrayaan engine room puzzle

A friend of mine had a question on this month's main puzzle, and so I would like to make one clarification regarding the two wires puzzle. The rate of burning of the two wires may be termed as "fixed but unknown". The first wire may burn as follows : 1 minute for the first 1%, another 2 minutes for the next 1 % and so on. At the end of 10 minutes, only 9% of the wire may have burned. However, since each wire takes an hour to burn through, the rest of the 91% of the first wire will burn in the next 50 minutes. The wire may be burned from either end. Similarly for the second wire.

Note that the way that the second wire burns may not be the same as the way that the first wire burns. Thus, the second wire may burn as follows : 2 minutes for the first 1%, 4 minutes for the next 1% and so on. At the end of 10 minutes, only 3% of the wire may have burned. But since the wire takes an hour to burn through, the rest of the 97% of the second wire would burn in the next 50 minutes. I use the term "fixed but unknown" because while the way the two wires burn is not known, the way the two wires burn does not change over the period of time in question.

(Chandrayaan Engine Room) Chandrayaan-12 has run into trouble. The problem is in the engine room, and the initial investigation into the problem has revealed that the positron motor needs to be restarted. This needs to be done exactly 45 minutes after the neutrino drive is turned off. However, the clocks in Chandrayaan are no longer reliable. All you have are two wires. The two wires each take exactly an hour to burn. They don't burn uniformly, however. So, for instance, the first half of the first wire may take 13 minutes to burn and the second half 47 minutes. Is it possible to measure out exactly 45 minutes using the two wires? If so, how?

Update: Mathematically speaking, let the length of the first wire that burns in time t be f1(t). This function is not known. It could be of the form [ f1(t) = k.t ], but it could be quite different as well. You don't need to understand any advanced mathematics to solve the problem, however, and for this reason, we have avoided using mathematical notation for the problem.