GMATBusters wrote:
In a refinery, the capacity of oil tank A is 70 percent of the capacity of oil tank B. How many more gallons of oil are in tank A than in tank B?
1) Tank A is 90 percent full; tank B is 50 percent full
2) When full, tank A contains 50,000 gallons of oil
Given: In a refinery, the capacity of oil tank A is 70 percent of the capacity of oil tank B. Let
A = the capacity of oil tank A
So,
0.7A = the capacity of oil tank B
Target question: How many more gallons of oil are in tank A than in tank B? Statement 1: Tank A is 90 percent full; tank B is 50 percent full This means 0.9
A = the volume of oil in tank A
And 0.5(
0.7A) = the volume of oil in tank B
In other words,
0.35A = the volume of oil in tank B
To answer the
target question, we need to calculate the value of 0.9
A -
0.35ASince we don't know the value of A, there's no way to calculate 0.9
A -
0.35AStatement 1 is NOT SUFFICIENT
Statement 2: When full, tank A contains 50,000 gallons of oilIn other words, A = 50,000
Clearly NOT SUFFICIENT
Statements 1 and 2 combined Statement 1 tells us that the answer the
target question is 0.9
A -
0.35AStatement 2 tells us that
A = 50,000Since we COULD plug
A = 50,000 into the expression 0.9
A -
0.35A, we COULD answer the
target question with certainty.
So, the combined statements are SUFFICIENT
Answer: C
Cheers,
Brent
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