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# In a small snack shop, the average (arithmetic mean) revenue

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Manager
Joined: 22 Sep 2010
Posts: 84
In a small snack shop, the average (arithmetic mean) revenue  [#permalink]

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Updated on: 09 Oct 2012, 03:55
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In a small snack shop, the average (arithmetic mean) revenue was $400 per day over a 10-day period. During this period, if the average daily revenue was$360 for the first 6 days, what was the average daily revenue for the last 4 days?

A. $420 B.$440
C. $450 D.$460
E. $480 Originally posted by pzazz12 on 22 Oct 2010, 05:49. Last edited by Bunuel on 09 Oct 2012, 03:55, edited 1 time in total. Edited the question. Manager Joined: 17 Aug 2010 Posts: 51 Re: In a small snack shop......... [#permalink] ### Show Tags 22 Oct 2010, 05:57 4 pzazz12 wrote: In a small snack shop, the average (arithmetic mean) revenue was$400 per day over a 10-day period. During this period, if the average daily revenue was $360 for the first 6 days, what was the average daily revenue for the last 4 days? A.$420
B. $440 C.$450
D. $460 E.$480

D. $460 is my answer. 400 = x/10 x = 4000 For first 6 days = 360 * 6 =$2160

therefore for the last 4 days revenue is $4000 -$2160 = 3840
hence, airthmatic mean = 3840/4 = $460 Please let me know the OA. Also, I am very bad in explaining things. I am waiting for Bunuel to respond. He is extremly good in explaining solution. _________________ I don't want kudos.. I want to see smile on your face if I am able to help you.. which is priceless. Math Expert Joined: 02 Sep 2009 Posts: 47983 Re: In a small snack shop......... [#permalink] ### Show Tags 22 Oct 2010, 05:58 3 pzazz12 wrote: In a small snack shop, the average (arithmetic mean) revenue was$400 per day over a 10-day period. During this period, if the average daily revenue was $360 for the first 6 days, what was the average daily revenue for the last 4 days? A.$420
B. $440 C.$450
D. $460 E.$480

The average revenue was $400 per day over a 10-day period --> total revenue over 10-day period is 10*$400=$4,000; The average daily revenue was$360 for the first 6 days --> total revenue for the first 6 days is 6*$360=2,160; Total revenue for the last 4 days is$4,000-2,160=$1,840; Average daily revenue for the last 4 days is$1,840/4=$460. Answer: D. _________________ Manager Joined: 17 Aug 2010 Posts: 51 Re: In a small snack shop......... [#permalink] ### Show Tags 22 Oct 2010, 06:00 1 Like I said, what Bunuel says is OA for me. _________________ I don't want kudos.. I want to see smile on your face if I am able to help you.. which is priceless. Intern Joined: 01 Oct 2010 Posts: 1 Re: In a small snack shop......... [#permalink] ### Show Tags 23 Oct 2010, 06:17 1 I solved it in another way, but not sure whether its correct. Can some one help me by validating.. Let 'x' be the average daily revenue for last 4 days. [6(360)+4(x)]/10 = 400 solving, x = 460 Thanks in advance Intern Joined: 15 Apr 2010 Posts: 46 Re: In a small snack shop......... [#permalink] ### Show Tags 08 Oct 2012, 22:33 2 weighted average total 10 days, avg10 of this period is 400 first 6 days avg6 is 360 which is deltaAvg6 = 40 away from the overall avg10 last 4 day avg4 must have more weight to pull the avg10 to 400 (if 5 days-5 days then last 5 must have 440 so that avg10 is pulled back to 400, but this is 6/4, so we know last 4 days avg must have much more weight, so avg4 > 440, eliminate few choices) since ratio of weight of 2 periods is 6/4 = 3/2, the avg4 must compensate for the loss of deltaAvg6 a 3/2 amount of deltaAvg6 so that the avg10 is pulled back to 400. therefore the last 4 days must have deltaAvg4 = 3/2 * deltaAvg6 = 3/2 * 40 = 60. so avg4 = 400 + deltaAvg4 = 400 + 60 = 460 --> D Director Status: My Thread Master Bschool Threads-->Krannert(Purdue),WP Carey(Arizona),Foster(Uwashngton) Joined: 28 Jun 2011 Posts: 837 Re: In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 09 Oct 2012, 07:05 460 400 x 10= 4000 360 x 6 = 2160 4000-2160 = 1840/4=460 Manager Joined: 13 Feb 2012 Posts: 141 Location: Italy Concentration: General Management, Entrepreneurship GMAT 1: 560 Q36 V34 GPA: 3.1 WE: Sales (Transportation) Re: In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 15 Dec 2012, 08:47 Bunuel's way of solving is definitely the most straight forward one; thanks! _________________ "The Burnout" - My Debrief Kudos if I helped you Andy Intern Joined: 24 Apr 2012 Posts: 48 Re: In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 16 Dec 2012, 04:08 Ans: the total revenue for 10 days is 10x400=4000 and the total revenue for first 6 days is 6x360=2160, so the average for last 4 days will be (4000-2160)/4 = 460 (D). _________________ www.mnemoniceducation.com TURN ON YOUR MINDS!!! Senior Manager Joined: 23 Oct 2010 Posts: 361 Location: Azerbaijan Concentration: Finance Schools: HEC '15 (A) GMAT 1: 690 Q47 V38 Re: In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 03 Jul 2013, 10:28 (400-360)*6/4=60 400+60=460 _________________ Happy are those who dream dreams and are ready to pay the price to make them come true I am still on all gmat forums. msg me if you want to ask me smth Director Joined: 10 Mar 2013 Posts: 561 Location: Germany Concentration: Finance, Entrepreneurship GMAT 1: 580 Q46 V24 GPA: 3.88 WE: Information Technology (Consulting) In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 19 Aug 2015, 02:03 I've solved it using weighted average formula: So, 360 is 40 less then the average of 400 -> -40 * 6 Days; We have 4 Days and need to calculate the revenue =X 6*(-40) + 4*x=0 X=60, so it means that for the last 4 days the revenue was 60 above the average = 400+60 =460 (D) Time: < 1 minute _________________ When you’re up, your friends know who you are. When you’re down, you know who your friends are. Share some Kudos, if my posts help you. Thank you ! 800Score ONLY QUANT CAT1 51, CAT2 50, CAT3 50 GMAT PREP 670 MGMAT CAT 630 KAPLAN CAT 660 Manager Joined: 26 Nov 2014 Posts: 96 In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 04 Sep 2015, 05:37 In a small snack shop, the average (arithmetic mean) revenue was$400 per day over a 10-day period. During this period, if the average daily revenue was $360 for the first 6 days, what was the average daily revenue for the last 4 days? Avg revenue per day = 400 Total revenue for 10 days = 4000 Avg Revenue for first 6 days = 360 Total revenue for first 6 days = 360 x 6 = 2160 Total revenue for 10 days = Total revenue for first 6 days + Total revenue for last 4 days 4000 = 2160 + X X=1840, which is Total revenue for last 4 days Avg revenue for last 4 days = $$\frac{1840}{4}$$ = 460. _________________ Consider Kudos for my post, if it is helpful. TIA Target Test Prep Representative Status: Founder & CEO Affiliations: Target Test Prep Joined: 14 Oct 2015 Posts: 3176 Location: United States (CA) Re: In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 21 Jun 2016, 10:21 2 pzazz12 wrote: In a small snack shop, the average (arithmetic mean) revenue was$400 per day over a 10-day period. During this period, if the average daily revenue was $360 for the first 6 days, what was the average daily revenue for the last 4 days? A.$420
B. $440 C.$450
D. $460 E.$480

This is a problem testing us on our knowledge of weighted averages. To solve, we can set up a weighted average equation:

(Revenue for first 6 days + Revenue for final 4 days)/10 days = 400

We know that the average revenue for the first 6 days was $360. We let r be the average daily revenue for the final four days, so we have (360 x 6 + 4r)/10 = 400 2,160 + 4r = 4,000 4r = 1,840 r = 460 Answer is D. _________________ Scott Woodbury-Stewart Founder and CEO GMAT Quant Self-Study Course 500+ lessons 3000+ practice problems 800+ HD solutions CEO Joined: 12 Sep 2015 Posts: 2706 Location: Canada In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 30 Jul 2016, 07:52 1 Top Contributor pzazz12 wrote: In a small snack shop, the average (arithmetic mean) revenue was$400 per day over a 10-day period. During this period, if the average daily revenue was $360 for the first 6 days, what was the average daily revenue for the last 4 days? A.$420
B. $440 C.$450
D. $460 E.$480

If the average (mean) daily revenue over 10 days is $400/day, then the TOTAL 10-DAY REVENUE = (10)($400) = $4000 The average daily revenue for the first 6 days is$360. So, the TOTAL 6-DAY REVENUE = (6)($360) =$2160

So, the TOTAL REVENUE for the last 4 days = $4000 -$2160 = $1840 So, the AVERAGE daily revenue for those 4 days =$1840/4 = $460 Answer: RELATED VIDEO _________________ Brent Hanneson – Founder of gmatprepnow.com Director Joined: 02 Sep 2016 Posts: 734 Re: In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 01 Apr 2017, 09:36 pzazz12 wrote: In a small snack shop, the average (arithmetic mean) revenue was$400 per day over a 10-day period. During this period, if the average daily revenue was $360 for the first 6 days, what was the average daily revenue for the last 4 days? A.$420
B. $440 C.$450
D. $460 E.$480

Total revenue for 10 days= 400*10= 4000
Total revenue for 6 days= 360*6= 2160

Thus the total revenue for remaining 4 days would be 4000-2160=1840

The average revenue for 4 days= 1840/4= 460
Manager
Joined: 09 Jan 2016
Posts: 120
GPA: 3.4
WE: General Management (Human Resources)
Re: In a small snack shop, the average (arithmetic mean) revenue  [#permalink]

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02 Jun 2017, 23:08
pzazz12 wrote:
In a small snack shop, the average (arithmetic mean) revenue was $400 per day over a 10-day period. During this period, if the average daily revenue was$360 for the first 6 days, what was the average daily revenue for the last 4 days?

A. $420 B.$440
C. $450 D.$460
E. $480 Total revenue 400* 10 = 4000 first 6 days = 360 *6 = 2160 rest of the four days = 1840 4x = 1840 X= 360 Manager Joined: 07 Jun 2017 Posts: 175 Location: India Concentration: Technology, General Management GMAT 1: 660 Q46 V38 GPA: 3.6 WE: Information Technology (Computer Software) Re: In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 26 Sep 2017, 00:00 The below is another method(easier) 400-360 = 40 for 6 days 40*6 = 240 this 240 need to be divide by remaining 4 days = 60 60 need to added to the average = 400+60 = 460 answer 460 _________________ Regards, Naveen email: nkmungila@gmail.com Please press kudos if you like this post Intern Joined: 31 Oct 2016 Posts: 3 Re: In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 18 Oct 2017, 11:51 360*6 +4x= 400*10 4x= 1840 x= 460 EMPOWERgmat Instructor Status: GMAT Assassin/Co-Founder Affiliations: EMPOWERgmat Joined: 19 Dec 2014 Posts: 12196 Location: United States (CA) GMAT 1: 800 Q51 V49 GRE 1: Q170 V170 Re: In a small snack shop, the average (arithmetic mean) revenue [#permalink] ### Show Tags 21 Feb 2018, 21:03 Hi All, There are a number of ways to "do the math" on this type of question. Using the standard Average Formula will work perfectly here, and you'll be asked to use it a couple of times over the course of the Quant section, so you shouldn't try to avoid it. That having been said, there's a weighted average "pattern" that can be used against this question: The average of the 10 days =$400

The average for the first 6 days = $360. This means that - on each of the first 6 days - each day was$40 "behind" the average. To get the average "up" to $400, the remaining 4 days have to "make up" for that deficit… 6 x$40 = $240 "behind" The last 4 days have to be above 400 by an amount that will make up for the$240.

$240/4 =$60. This means that each of the last 4 days needs to be $460 for the overall average to be$400.

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Intern
Joined: 10 Apr 2018
Posts: 43
Re: In a small snack shop, the average (arithmetic mean) revenue  [#permalink]

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17 Aug 2018, 12:30
Hello,

To avoid calculations we can use deviation method

400=360+(4x/10)
4x= 400
x= 100
=360+100= 460
hence option D
Re: In a small snack shop, the average (arithmetic mean) revenue &nbs [#permalink] 17 Aug 2018, 12:30

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