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19 Jan 2026, 03:45
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
65% (02:13) correct
35%
(02:06)
wrong
based on 211
sessions
History
Date
Time
Result
Not Attempted Yet
George’s Gas Station gets fuel from two different fuel suppliers: Dyon and Brian’s Biofuels. Each supplier provides fuel with a different percentage of ethanol, and George mixes them together in his supply tank. If George currently has 1,000 gallons of fuel at 11 percent ethanol in his supply tank, how much fuel from Brian’s Biofuels would he need to add to achieve a final mixture that is 12 percent ethanol?
(1) Brian’s Biofuels provides fuel with 80 percent ethanol.
(2) The mixture currently in George’s supply tank has 10 gallons of fuel from Brian’s Biofuels and 990 gallons of fuel from Dyon.
(1) Brian’s Biofuels provides fuel with 80 percent ethanol.
(2) The mixture currently in George’s supply tank has 10 gallons of fuel from Brian’s Biofuels and 990 gallons of fuel from Dyon.
25 Apr 2026, 22:23
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To determine the amount of fuel from Brian’s Biofuels needed, we can use the following calculation based on the total ethanol content.
Let x be the number of gallons of fuel from Brian’s Biofuels to be added.
1,000×0.11=110
According to Statement (1), Brian’s Biofuels provides fuel with 80 percent ethanol, meaning adding x gallons of this fuel adds 0.80x gallons of ethanol. The goal is a final mixture of 12 percent ethanol in a total volume. Sufficient.
Statement (2) provides information about the current composition of the tank (10 gallons from Brian’s and 990 from Dyon), which is consistent with the initial conditions provided in the question but is not required to solve for the additional amount needed. Not Sufficient
Therefore, statement (1) alone is sufficient to solve the problem.
ANS = A
Let x be the number of gallons of fuel from Brian’s Biofuels to be added.
1,000×0.11=110
According to Statement (1), Brian’s Biofuels provides fuel with 80 percent ethanol, meaning adding x gallons of this fuel adds 0.80x gallons of ethanol. The goal is a final mixture of 12 percent ethanol in a total volume. Sufficient.
Statement (2) provides information about the current composition of the tank (10 gallons from Brian’s and 990 from Dyon), which is consistent with the initial conditions provided in the question but is not required to solve for the additional amount needed. Not Sufficient
Therefore, statement (1) alone is sufficient to solve the problem.
ANS = A
26 Apr 2026, 05:25
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Answer is A.
This is a Data Sufficiency mixture problem, specifically testing whether you can set up the weighted average equation and recognize what information is actually needed.
The setup: George has 1,000 gallons at 11% ethanol. He wants to add x gallons from Brian's to reach 12% ethanol. So:
(1000 * 0.11 + x * B) / (1000 + x) = 0.12
where B is Brian's ethanol percentage. Simplifying:
110 + Bx = 120 + 0.12x
Bx - 0.12x = 10
x(B - 0.12) = 10
x = 10 / (B - 0.12)
So we need exactly one thing: the value of B (Brian's ethanol %).
Statement (1): Brian's Biofuels provides 80% ethanol. That gives us B = 0.80, and x = 10 / (0.80 - 0.12) = 10 / 0.68. Solvable. SUFFICIENT.
Statement (2): The current tank has 10 gallons from Brian's and 990 from Dyon. This tells us the composition of the existing 1,000 gallons, but NOT what percentage of ethanol Brian's fuel contains. We still have 10 * B + 990 * D = 110, which is one equation with two unknowns. NOT SUFFICIENT.
Answer: A.
The trap most people fall into is thinking Statement (2) somehow tells them more than it does. It actually just restates information consistent with the problem setup (10 gal from Brian + 990 from Dyon = 1000 gal total at 11%). Redundant information, not new information.
Classic DS trap: information that looks useful but only confirms what you already know.
This is a Data Sufficiency mixture problem, specifically testing whether you can set up the weighted average equation and recognize what information is actually needed.
The setup: George has 1,000 gallons at 11% ethanol. He wants to add x gallons from Brian's to reach 12% ethanol. So:
(1000 * 0.11 + x * B) / (1000 + x) = 0.12
where B is Brian's ethanol percentage. Simplifying:
110 + Bx = 120 + 0.12x
Bx - 0.12x = 10
x(B - 0.12) = 10
x = 10 / (B - 0.12)
So we need exactly one thing: the value of B (Brian's ethanol %).
Statement (1): Brian's Biofuels provides 80% ethanol. That gives us B = 0.80, and x = 10 / (0.80 - 0.12) = 10 / 0.68. Solvable. SUFFICIENT.
Statement (2): The current tank has 10 gallons from Brian's and 990 from Dyon. This tells us the composition of the existing 1,000 gallons, but NOT what percentage of ethanol Brian's fuel contains. We still have 10 * B + 990 * D = 110, which is one equation with two unknowns. NOT SUFFICIENT.
Answer: A.
The trap most people fall into is thinking Statement (2) somehow tells them more than it does. It actually just restates information consistent with the problem setup (10 gal from Brian + 990 from Dyon = 1000 gal total at 11%). Redundant information, not new information.
Classic DS trap: information that looks useful but only confirms what you already know.
