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# In a retail store, the average (arithmetic mean) sale for month M was

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In a retail store, the average (arithmetic mean) sale for month M was  [#permalink]

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Updated on: 09 Dec 2018, 09:03
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Difficulty:

45% (medium)

Question Stats:

58% (01:18) correct 42% (01:29) wrong based on 292 sessions

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Project DS Butler: Day 34: Data Sufficiency (DS68)

In a retail store, the average (arithmetic mean) sale for month M was d dollars. Was the average (arithmetic mean) sale for month J at least 20 percent higher than that for month M?

(1) For month M, total revenue from sales was $3,500. (2) For month J, total revenue from sales was$6,000.

In the solution, it is mentioned that

Quote:
This statement provides no information as to the number of sales so there is no way to determine the size of average scale.

My confusion is whether the fact that no of days of a month can be 28 or 30 or 31 is the main culprit or any other reason is present because of which we are not able to solve the problem.

Originally posted by Nevernevergiveup on 11 Sep 2015, 09:34.
Last edited by gmatbusters on 09 Dec 2018, 09:03, edited 3 times in total.
RENAMED THE TOPIC.
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Re: In a retail store, the average (arithmetic mean) sale for month M was  [#permalink]

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14 Sep 2015, 22:45
You are right. With the mean and no of days, you can count total sales.

Total sales = mean * no of days

However, in both cases, we have only total sales given. There's no way to find mean without no of days. So, both are together insufficient. Hence (E)
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Re: In a retail store, the average (arithmetic mean) sale for month M was  [#permalink]

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17 Nov 2015, 01:36
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Mechmeera wrote:
In a retail store, the average (arithmetic mean) sale for month M was d dollars. Was the average (arithmetic mean) sale for month J at least 20 percent higher than that for month M?

(1) For month M, total revenue from sales was $3,500. (2) For month J, total revenue from sales was$6,000.

In the solution, it is mentioned that

Quote:
This statement provides no information as to the number of sales so there is no way to determine the size of average scale.

My confusion is whether the fact that no of days of a month can be 28 or 30 or 31 is the main culprit or any other reason is present because of which we are not able to solve the problem.

Hi, that is not the reason. The question isn't talking about average daily sales, but about average sale amount. For example, there can be more than 1 sale per day, it could be that they had 100 sales in Month M and 1 sale in month J or vice versa. So the number of days per month is not the reason for answer E, its the number of sales that we need to know.
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Re: In a retail store, the average (arithmetic mean) sale for month M was  [#permalink]

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17 Nov 2015, 01:39
HardWorkBeatsAll wrote:
You are right. With the mean and no of days, you can count total sales.

Total sales = mean * no of days

However, in both cases, we have only total sales given. There's no way to find mean without no of days. So, both are together insufficient. Hence (E)

I highlighted the portion that I do not agree with.

Total sales = average sale * number of sales, not number of days.
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Re: In a retail store, the average (arithmetic mean) sale for month M was  [#permalink]

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19 Nov 2015, 18:54
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Hi Mechmeera,

Since the prompt focuses on the average SALE per month, we need to know the TOTAL revenue and the TOTAL number of sales (re: the total number of 'transactions'). The number of days in the month has NO impact on this question.

You'll notice that the nothing in the prompt ever describes the total number of transactions in either month M or month J, so there is no way to determine the average sale for either month (nor how those averages relate to one another).

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(2) For month J, total revenue from sales was $6,000. (A) Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the question asked (B) Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the question asked (C) BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient (D) EACH statement ALONE is sufficient to answer the question asked (E) Statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data are needed Question is asking for comparison between Average Sale of Month M and Month J. Average sale = $$\frac{Total Revenue from All Sales}{No. of Sales}$$ Neither of the options gives the No. of sales, so Answer is E. EMPOWERgmat Instructor Status: GMAT Assassin/Co-Founder Affiliations: EMPOWERgmat Joined: 19 Dec 2014 Posts: 14188 Location: United States (CA) GMAT 1: 800 Q51 V49 GRE 1: Q170 V170 Re: In a retail store, the average (arithmetic mean) sale for month M was [#permalink] ### Show Tags 25 Sep 2016, 20:10 Hi rakaisraka, Since the prompt focuses on the average SALE per month, we need to know the TOTAL revenue and the TOTAL number of sales (re: the total number of 'transactions'). The number of days in the month has NO impact on this question. You'll notice that the nothing in the prompt ever describes the total number of transactions in either month M or month J, so there is no way to determine the average sale for either month (nor how those averages relate to one another). Final Answer: GMAT assassins aren't born, they're made, Rich _________________ 760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com *****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***** # Rich Cohen Co-Founder & GMAT Assassin Special Offer: Save$75 + GMAT Club Tests Free
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Re: In a retail store, the average (arithmetic mean) sale for month M was  [#permalink]

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09 Dec 2018, 09:40
Average sale = total revenue/total no of sales.

Question asks about the average sale and the a) and b) gives the total revenue.

Since the denominator value is not given, we cannot calculate the average sale.

Hence E.
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Re: In a retail store, the average (arithmetic mean) sale for month M was  [#permalink]

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15 Dec 2018, 05:26
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Solution:
Question is asking for the comparison between Average Sale of Month M and Month J.
Here the trap point is taking total sales as Total sales = mean * no of days
But the Average sale is given by $$\frac{(Total Revenue from All sales)}{(No of sales)}$$
To determine the average sale we need to know total revenue and number of sales.

Analysis of Statement 1: For month M, total revenue from sales was $3,500. Here we know only about total revenue but no information about the number of sales. Therefore the statement 1 is not sufficient. We can eliminate options A and D. Analysis of Statement 2: For month J, total revenue from sales was$6,000.
Here also we know only about total revenue but no information about the number of sales.
Therefore the statement 2 is not sufficient.

Combining the statements 1 & 2; we get:
From statement 1: We know total revenue from sales was $3,500 for Month M. From Statement 2: We know total revenue from sales was$6,000 for Month J
Still, we do not the number of sales, so we cannot answer the question.

So, the correct answer option is “E”.

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Re: In a retail store, the average (arithmetic mean) sale for month M was   [#permalink] 15 Dec 2018, 05:26
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