Bunuel wrote:
If O and ∆ are digits. What is the value of ∆.OOO + O. ∆∆∆?
(1) ∆ + O = 10
(2) ∆ = O
Target question: What is the value of ∆.OOO + O. ∆∆∆?This is a great candidate for
rephrasing the target questionLet's start by making a few observations.
Notice that 0.222 = 2(0.111), 0.333 = 3(0.111), 0.444 = 4(0.111), etc.
Likewise, 0.∆∆∆ =∆(0.111) and 0.OOO = O(0.111) and
So, ∆.OOO + O. ∆∆∆ = [∆ + O(0.111)] + [O + ∆(0.111)]
= 1.111∆ + 1.111O
= 1.111(∆ + O)
REPHRASED target question: What is the value of 1.111(∆ + O)?Aside: the video below has tips on rephrasing the target question Statement 1: ∆ + O = 10 So,
1.111(∆ + O) = 1.111(10) = 11.11Perfect!
Since we can answer the
REPHRASED target question with certainty, statement 1 is SUFFICIENT
Statement 2: ∆ = OThis does not help us answer the REPHRASED target question.
Consider these two conflicting cases:
Case a: ∆ = O = 1. In this case, the answer to the REPHRASED target question is
1.111(∆ + O) = 1.111(1 + 1) = 1.111(2) = 2.222 Case a: ∆ = O = 3. In this case, the answer to the REPHRASED target question is
1.111(∆ + O) = 1.111(3 + 3) = 1.111(6) = 6.666 Since we cannot answer the
REPHRASED target question with certainty, statement 2 is NOT SUFFICIENT
Answer: A
Cheers,
Brent
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