someone please help w/ this Q!

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someone please help w/ this Q!

by smeyers » Mon Apr 12, 2010 3:55 pm
A certain store found that last year the average (arithmetic mean) monthly sales from January through October was $120,000. In November and December, the monthly sales were 3 and 5 times, respectively, the average for the other 10 months. What was the store's average monthly sales last year?

A) $180,000
B) $216,000
C) $252,000
D) $318,000
E) $360,000
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by dmateer25 » Mon Apr 12, 2010 4:00 pm
smeyers wrote:A certain store found that last year the average (arithmetic mean) monthly sales from January through October was $120,000. In November and December, the monthly sales were 3 and 5 times, respectively, the average for the other 10 months. What was the store's average monthly sales last year?

A) $180,000
B) $216,000
C) $252,000
D) $318,000
E) $360,000
120,000 * 10 = 1,200,000 (sales for Jan - Oct)

120,000 * 3 = 360,000 (sales for Nov)

120,000 * 5 = 600,000 (sales for Dec)

1,200,000 + 360,000 + 600,000 = 2,160,000 (sales Jan - Dec)


2,160,000/12 = 180,000 (average sales for the year)

A

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by grockit_andrea » Mon Apr 12, 2010 4:05 pm
Unless I'm missing something here, the answer is A, $180,000. $120,000 a month for 10 months, plus $360,000 for November and $600,000 for December equals $2,160,000. That's then divided by the 12 months of the year, for a monthly average of $180,000.

(120,000 x 10) + (3 x 120,000) + (5 x 120,000)
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by eaakbari » Thu Apr 15, 2010 6:30 am
((120,000 x 10) + (3 x 120,000) + (5 x 120,000))/12


120,000(10+3+5)/12



120,000*18/12


=180,000

A
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