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The Arnolds purchased 550 square feet of Kentucky Gem sod at $1.89 per 10 Jan 2016, 08:47
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67% (02:36) correct 33% (02:57) wrong based on 138 sessions

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The Arnolds purchased 550 square feet of Kentucky Gem sod at $1.89 per square foot and 270 square feet of Zelzea Blue sod at $1.38 per square foot. What was the approximate average price per square foot paid for all the sod?

A. $1.63
B. $1.64
C. $1.68
D. $1.72
E. $1.76
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D
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The Arnolds purchased 550 square feet of Kentucky Gem sod at $1.89 per 10 Jan 2016, 10:32
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Bunuel
The Arnolds purchased 550 square feet of Kentucky Gem sod at $1.89 per square foot and 270 square feet of Zelzea Blue sod at $1.38 per square foot. What was the approximate average price per square foot paid for all the sod?

A. $1.63
B. $1.64
C. $1.68
D. $1.72
E. $1.76
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Answer D

Average price = (550*1.89)+(270*1.38)/550+270=1.72 (Approx)
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GMAT Focus 1: 735 Q90 V89 DI81
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The Arnolds purchased 550 square feet of Kentucky Gem sod at $1.89 per 15 Jan 2016, 09:10
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Bunuel
The Arnolds purchased 550 square feet of Kentucky Gem sod at $1.89 per square foot and 270 square feet of Zelzea Blue sod at $1.38 per square foot. What was the approximate average price per square foot paid for all the sod?

A. $1.63
B. $1.64
C. $1.68
D. $1.72
E. $1.76
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Hi,
another method apart from what Praveengeol has shown..
THis weighted average method is handy incase we want to avoid dense calculations..
The logic is the average will move towards more weight/qty in the same ratio as two quantities

here two quantities are 550 and 270 almost 2:1..
so the average will be closer to the bigger qty by a ratio of 1/3 (opposite of ratio 2:1)..

lets see the averages 1.89 and 1.38... their difference is .51....1/3 of .51= .17..
so average will be 1.89-.17=1.72..
D
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The Arnolds purchased 550 square feet of Kentucky Gem sod at $1.89 per 15 Jan 2016, 13:05
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Similar to Chetan2u's method, since we want to know the weighted average of only 2 quantities, then we can simply use the ratio of the quantities rather than the quantities themselves. In this case, the ratio of the quantities can be approximated as 2:1 Kentucky Gem to Zelzea Blue. With that information, we can use the ratio instead of the quantities to calculate the weighted average.

Assume 2 units of Kentucky Gem = 2*1.89 = 3.78
Assume 1 unit of Zelzea Blue = 1*1.38 = 1.38

Add them up and divide by 3: \(\frac{3.78 + 1.38}{3} = \frac{5.16}{3} = 1.72\)

Answer D


You could approximate even more by saying 1.89 ≈ 1.90, and 1.38 ≈ 1.40

Then you'd get a total of 5.20/3 = 1.7333 which is closest to 1.72. But we'd have to be careful here, since the answer choices are relatively close together, and we have approximated 3 quantities by this point, so I would start to be less confident in my answer. In general, approximation is good if the answer choices are spread out, but don't approximate where it doesn't make your life easier, or where it will add too much uncertainty.
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The Arnolds purchased 550 square feet of Kentucky Gem sod at $1.89 per 10 Sep 2025, 04:45
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