Hi All,
While this question certainly looks "crazy", it can be solved rather easily by TESTing VALUES, staying organized and looking for logical patterns.
We're told that there are 2 lists of numbers (List L and List M), but we're NOT told ANYTHING about the lists. We can make them as simple of complex as we choose. I choose to make them SIMPLE....
List L: {2, 2} Average = 2, number of terms = 2
List M: {3, 3, 3} Average = 3, number of terms = 3
The prompt assigns a number of variables to different terms:
X = # of terms in List L
Y = # of terms in List M
P = Average of List L
Q = Average of ALL the terms in Lists L and M.
Using the above 2 lists as reference:
X = 2
Y = 3
P = 2
Q = 13/5 = 2.6
We're asked for the AVERAGE of LIST M. Before you jump into the answer choices, think about what you're asked for....The AVERAGE of List M.....Since list M has 3 terms, we will eventually divide a sum by 3. Now, look at the answer choices.....which answers do NOT do that.... You can eliminate Answer A (it divides by 2) and Answer D (it divides by 5). Now, we just have to check 3 answers; we're looking for an answer that is the AVERAGE of List M, so we're looking for the number 3.
Answer B: (QY-PX)/Y = (7.8 - 4)/3 = 3.8/3 This is clearly too small. Eliminate B.
Answer C: (P+Q)X/Y = (4.6)(2)/3 = 9.2/3 This is too big. Eliminate C.
Answer E is all that's left, but I'll check it just to be sure....
Answer E: [(Q-P)X +QY]/Y = [(0.6)(2) +7.8]/3 = 9/3 = 3. This is a MATCH.
Final Answer:
GMAT assassins aren't born, they're made,
Rich
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