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Last September the sales total for a certain car dealership was 400%

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Last September the sales total for a certain car dealership was 400%  [#permalink]

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New post Updated on: 05 Jul 2015, 07:16
1
11
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

61% (01:55) correct 39% (02:03) wrong based on 400 sessions

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Last September the sales total for a certain car dealership was 400% greater than the average monthly sales total for the other 11 months. The sales total for September was approximately what percent of the year´s sales?

A. 15 %
B. 27%
C. 31%
D. 42%
E. 75%

Originally posted by Ravshonbek on 21 Aug 2007, 18:53.
Last edited by Bunuel on 05 Jul 2015, 07:16, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
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Re: Math Question  [#permalink]

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New post 31 Aug 2008, 20:26
2
2
such problems are best done , by plugging

let every month sale or average sale per month (for 11 months) be 1 car / month.
so sale in september = 400% of monthly avg ... sorry 400% greater ( notice the difference) this is where we make mistakes.
= (400/100)+1 = 5 times avg monthly sale
so sep sale/ total yr sale= 5/16 = (3 and something) %. from the ans , only C matches.
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Re: Math Question  [#permalink]

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New post 31 Aug 2008, 20:29
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HVD1975 wrote:
Last september the sales total for a certain car dealership was 400% greater than the average (arithmetic mean) monthly sales total for the other 11 months of the year. The sales total for September was approximately what percent of the year's sales?

a) 15%
b) 27%
c) 31%
d) 42%
e) 75%


11 moth avg = x
11 month total = 11x
sept = 400% of x + x = 5x
sept/totoal = =5x/(11x+5x) = =31%
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Re: Math Question  [#permalink]

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New post 31 Aug 2008, 22:17
HVD1975 wrote:
Last september the sales total for a certain car dealership was 400% greater than the average (arithmetic mean) monthly sales total for the other 11 months of the year. The sales total for September was approximately what percent of the year's sales?

a) 15%
b) 27%
c) 31%
d) 42%
e) 75%


5x/11x+5x = 5/16 = 31%
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Error in Kaplan question  [#permalink]

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New post 20 Oct 2009, 07:42
Hi guys, I just did the following question:

Last September the sales total for at certain car dealership was 400% greater than the average (arithmetic mean) monthly sales total for the other 11 months of the year. The sales total for September was approximately what percent of the years sales?

1. 15%
2. 27%
3. 31%
4. 42%
5. 75%

My way of solving this is normalizing the average monthly sales on the other 11 months to =1. Thus the sales in September is 4 (400%*1) and therefore September made out: 4/(4+11)=4/15 of the years sales according to my logic.

Yet the OA suggests the same way of solving the question except that it claims that the sales in September is 1 + (400%*1) = 5, such that the fraction is 5/16 which is approximately 31%.

Would you tend to agree that this is an error in the software or am I completely missing something?
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Re: Error in Kaplan question  [#permalink]

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New post 20 Oct 2009, 10:32
1
andershv wrote:
Hi guys, I just did the following question:

Last September the sales total for at certain car dealership was 400% greater than the average (arithmetic mean) monthly sales total for the other 11 months of the year. The sales total for September was approximately what percent of the years sales?

1. 15%
2. 27%
3. 31%
4. 42%
5. 75%

My way of solving this is normalizing the average monthly sales on the other 11 months to =1. Thus the sales in September is 4 (400%*1) and therefore September made out: 4/(4+11)=4/15 of the years sales according to my logic.

Yet the OA suggests the same way of solving the question except that it claims that the sales in September is 1 + (400%*1) = 5, such that the fraction is 5/16 which is approximately 31%.

Would you tend to agree that this is an error in the software or am I completely missing something?


andershv

the question says 400% greater than avg of remaining 11 months so the OA explanation is correct
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Re: Error in Kaplan question  [#permalink]

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New post 20 Oct 2009, 20:40
1
1
Pay particular attention to asterixmatrix's point; the testmakers know that this is an easy trap to fall for, and will frequently include the trap as a wrong answer choice. % increase + 100% = % of total; since we are going up by 400%, we are therefore ending with a result of 500%, which we plug into our equation.
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Re: Last September the sales total for a certain car dealership was 400%  [#permalink]

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New post 30 Nov 2016, 14:16
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Top Contributor
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Ravshonbek wrote:
Last September the sales total for a certain car dealership was 400% greater than the average monthly sales total for the other 11 months. The sales total for September was approximately what percent of the year´s sales?

A. 15 %
B. 27%
C. 31%
D. 42%
E. 75%


Let's assign some nice values

Last September the sales total for a certain car dealership was 400% greater than the average monthly sales total for the other 11 months.
Let's say that the AVERAGE monthly sales for the other 11 months = $1
400% of $1 = $4
So, September's sales total = $1 + $4 = $5

So, the YEARLY total sales = (11)($1) + $5 = $16

The sales total for September was approximately what percent of the year´s sales?
$5/$16 = 31.25%

Answer: C
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Re: Last September the sales total for a certain car dealership was 400%  [#permalink]

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New post 08 Feb 2018, 09:21
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: Last September the sales total for a certain car dealership was 400% &nbs [#permalink] 08 Feb 2018, 09:21
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