Data Sufficiency

BTGmoderatorDC wrote:A tank containing water started to leak. Did the tank contain more than 30 gallons of water when it started to leak? (Note: 1 gallon = 128 ounces)

(1) The water leaked from the tank at a constant rate of 6.4 ounces per minute.
(2) The tank became empty less than 12 hours after it started to leak.

Given: A tank containing water started to leak

To find out: Did the tank contain more than 30 gallons of water when it started to leak?

Let's take each statement one by one.

(1) The water leaked from the tank at a constant rate of 6.4 ounces per minute.

Certainly insufficient as we do not know the duration for which the leak happened.

(2) The tank became empty less than 12 hours after it started to leak.

Certainly insufficient as we do not know the rate of the leak.

(1) and (2) together

Certainly, if the tank became empty quickly, say 1 minute after it started to leak, the answer is No, the tank did not contain more than 30 gallons of water when it started to leak.

However, if the tank became empty, say in 12 hours after it started to leak, and the volume of the water comes out to be more than 30 gallons, the answer would be Yes. There won't be a unique answer, thus, insufficient.

Let's calculate the leaked volume of water in 12 hours.

Leaked volume of water in 12 hours = (6.4/128)*(12*60) = 36 gallons > 30 gallons. The answer is Yes. No unique answer. Insufficient.

The correct answer: E

Hope this helps!

-Jay
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