innoPath Interview Question: there are 2 ropes. Each takes... | Glassdoor

Interview Question

Senior Software Engineer Interview Sunnyvale, CA

there are 2 ropes. Each takes 1 hour to totally burn off

 . But you cant say that half rope burns in 30 min. It is of irregular thickness. Using these 2 ropes how do you measure 45 minutes.

Interview Answer

2 Answers


burn first rope at 2 ends. Burn second rope on one end only. Now we know that it is half hour when first burns totally. at this time burn the second rope at other end also. Now the remianing of the second rope takes 15 min

Interview Candidate on Aug 13, 2010

Unfortunately, since the ropes do not burn at constant rates, you cannot assume that each half of a doubled-over rope will take 30 minutes to burn.

If the question stipulates that the ropes burn at a constant rate and you don't have a way to measure them, this answer works.

Correction to Answer/Question on Apr 18, 2013

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