Bunuel wrote:

Suppose you have access to a large vat of distilled water, several gallons large. You have two precise measuring pipettes, one to measure exactly 1/3 of an ounce and one to measure exactly 1/4 of an ounce. You can pour precisely measured amounts into a beaker, which initially is empty. You can use either pipette to remove distilled water from the vat or from the beaker and use either pipette to dispense water into either of those receptacles, but you cannot use either pipette to take any quantity of distilled water other than the amount for which it is designed. Which of the following represents, in ounces, a precise amount of distilled water you can transfer from the vat to the beaker?

I. 1/6

II. 1/7

III. 1/12

A. I only

B. III only

C. I and III only

D. II and III only

E. I, II, and III

Kudos for a correct solution.

The question is a nightmare..takes a lot of time to just simply read the question stem..even more is needed to comprehend it..

we can take 1/3 and pour from 1/3 to 1/4, and we are left with 1/3-1/4 = 1/12

so III is definitely true. A is out.

now..

we can pour this 1/12 into the beaker, and repeat the process. we get with another 1/12

we pour it again into the beaker

now, from the beaker we can take 2/12 or 1/6. so I is an answer. B and D are out.

1/7 - we can't get in any way, as 7 is not a multiple of 3 and 4 nor a factor of LCM of 3 and 4, so C is the answer.