sandy wrote:
Between 2011 and 2012, total costs per distinct customer increased by the greatest percent at which store?
(A) Store W
(B) Store X
(C) Store Y
(D) Store Z
(D) It cannot be determined from the information given.
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STORE WLet A = the total costs for 2011
Let B = the total number of customers for 2011
So, in 2011, the total cost per person =
A/BAccording to the table...
1.15A = the total costs for 2012
1.02B = the total number of customers for 2012
So, in 2012, the total cost per person =
1.15A/1.02BSo, the cost per person percent increase = [(
1.15A/1.02B) - (
A/B)]/(
A/B) =
0.13/1.02 ≈ 12.7%---------------------------------------------------------
STORE XLet C = the total costs for 2011
Let D = the total number of customers for 2011
So, in 2011, the total cost per person =
C/DAccording to the table...
1.04C = the total costs for 2012
1.14D = the total number of customers for 2012
So, in 2012, the total cost per person =
1.04C/1.14DSTOP! At this point, we can see that the cost per person actually
decreases from 2011 to 2012
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When we perform the same calculations for store Y, we get the cost per person percent increase =
0.07/1.05 ≈ 6.7% When we perform the same calculations for store Z, we see that the cost per person actually
decreases from 2011 to 2012
So, the greatest percent increase occurs with store W
Answer: A