Hi All,

If you're not sure how to approach this question, then you can TEST THE ANSWERS and do a bit of easy 'brute force' math to get to the solution.

We're told that the ratio of bleach to water is SUPPOSED to be 1:4, but that John accidentally puts in HALF the bleach that he's supposed to and ends up with 27 mL of total solution. We're asked for the amount of bleach (in mL) that he actually put in.

Let's start with the smallest answer and work our way up...

Answer E: 1.5

IF.... John put in 1.5 mL of bleach....

then he should have put in 3 mL of bleach and 12 mL of water...

the total of THIS mixture is 1.5 + 12 = 13.5 mL which is TOO SMALL (notice that this total is exactly HALF of what it should be....)

Answer D: 3

IF.... John put in 3 mL of bleach....

then he should have put in 6 mL of bleach and 24 mL of water...

the total of THIS mixture is 3 + 24 = 27 mL which is an exact MATCH for what we were told, so this MUST be the answer.

Final Answer:

GMAT assassins aren't born, they're made,

Rich

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# Rich Cohen

Co-Founder & GMAT Assassin

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