Best Answer Pickett, 25 November 2013 - 02:35 PM

Spoiler for Small assumption...

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Can we make the assumption that the beakers are either perfect cylinders or perfect rectangular prisms??

If we can assume that, then this can be done in 5 steps (might be better, I just haven't spent time looking) because of the fact that we can easily pour out enough liquid in any beaker to leave it EXACTLY half full (just start pouring, carefully, until the bottom corner of the beaker is level with the water):

A0, B0, C5, D5 **-- Initial configuration**

- A0, B4, C1, D5
**-- Pour C into B, filling B** - A0, B2, C3, D5
**-- Pour EXACTLY half of B back into C using the method above** - A3, B2, C3, D2
**-- Pour D into A, filling A** - A1, B4, C3, D2
**-- Pour A into B, filling B** - A1, B2, C3, D4
**-- Pour EXACTLY half of B into D using the method above.**

** Note the wording that I used above about leaving half of the liquid in the beaker...not pouring half of the liquid out. This is because if we had 3 gallons in B, and used the method I described above, we would still be left with 2 gallons in B, and only poured 1 out.