[ubuntu-mono] [Bug 752357] Re: Train question has wrong answer... and wrong explanation... and therefore wrong calculation built-in.

[Brink of Complexity]

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https://bugs.launchpad.net/bugs/752357

Title:
  Train question has wrong answer... and wrong explanation... and
  therefore wrong calculation built-in.

Status in “gbrainy” package in Ubuntu:
  New

Bug description:
  Binary package hint: gbrainy

  A train leaves the station at 30mph. 6 hours later, a second train
  leaves at 50mph. How long until the second train overtakes the first?

  This Gallilean Relativity question is easy to answer in a 30mph
  reference frame, where the first train is "standing still" 180mi
  (30mph x 6 hrs) from the "20mph" second train (50mph - 30mph).  The
  answer is clearly 9 hours (180mi / 20mph), but gbrainy thinks it's 15
  hours.

  gbrainy claims that the method to the answer is to multiply the speed
  of the *second* train by the time, and then divide by the difference
  in speed.  This, however, is backwards.  To get the true answer, we
  must multiply the speed of the *first* train by the time to get the
  difference in distance, and then divide by the difference in speed
  (the relative speed of the second train).

  To fix this bug, just change the calculation to reflect that the
  *first* train needs to be multiplied by the time, not the second
  train. That's it!

  ProblemType: Bug
  DistroRelease: Ubuntu 10.10
  Package: gbrainy 1.51-0ubuntu1
  ProcVersionSignature: Ubuntu 2.6.35-28.49-generic-pae 2.6.35.11
  Uname: Linux 2.6.35-28-generic-pae i686
  NonfreeKernelModules: nvidia wl
  Architecture: i386
  Date: Wed Apr  6 04:52:18 2011
  InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
  PackageArchitecture: all
  ProcEnviron:
   LANG=en_US.utf8
   SHELL=/bin/bash
  SourcePackage: gbrainy