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Re: The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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25 May 2016, 21:46
Attached is a visual that should help.
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Screen Shot 20160525 at 9.42.14 PM.png [ 51.22 KiB  Viewed 995 times ]
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Director
Status: Professional GMAT Tutor
Affiliations: AB, cum laude, Harvard University (Class of '02)
Joined: 10 Jul 2015
Posts: 637
Location: United States (CA)
Age: 38
GMAT 1: 770 Q47 V48 GMAT 2: 730 Q44 V47 GMAT 3: 750 Q50 V42
GRE 1: 337 Q168 V169
WE: Education (Education)

The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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10 Aug 2016, 08:43
ameyaprabhu wrote: is this really a 700 question, or is there some error? No, it's definitely not a 700level question, in my opinion. I added a "Sub600 question" tag. Only the original poster of the question can remove tags, as far as I can tell.
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Harvard grad and 99% GMAT scorer, offering expert, private GMAT tutoring and coaching, both inperson (San Diego, CA, USA) and online worldwide, since 2002.
One of the only known humans to have taken the GMAT 5 times and scored in the 700s every time (700, 710, 730, 750, 770), including verified section scores of Q50 / V47, as well as personal bests of 8/8 IR (2 times), 6/6 AWA (4 times), 50/51Q and 48/51V (1 question wrong).
You can download my official testtaker score report (all scores within the last 5 years) directly from the Pearson Vue website: https://tinyurl.com/y8zh6qby Date of Birth: 09 December 1979.
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Re: The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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10 Aug 2016, 12:27
let "X" be the cost of the meal excluding the 15% tax.
Now
> x+ 15% of x = 207 > 115x/100 = 207 > x = $180
No of people = 15 Cost per person = $180/15 = $12



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Re: The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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23 Jan 2017, 19:55
X+15%ofX=207 23X/20=207 X=180 180/15=12 Sent from my Lenovo A6020a46 using GMAT Club Forum mobile app



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Re: The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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05 Feb 2017, 21:07
Let the average price per person without gratuity for service be X
Now the overall price would be
X * 15 *{(100+15/100} = 207 > X * 15*1.15 = 207 > X = 207/(1.15*15) = 12



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Re: The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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28 Aug 2017, 14:24
enigma123 wrote: The price of lunch for 15 people was $207.00, including a 15 percent gratuity for service. What was the average price per person, EXCLUDING the gratuity?
(A) $11.73 (B) $12.00 (C) $13.80 (D) $14.00 (E) $15.87
Many students will incorrectly reason that, since $207 is 15% GREATER than the pretip total, then the pretip total must be 15% LESS than $207 (i.e., pretip total = 85% of $207) This is a common misconception that goes something like this: If A is k percent greater than B, then B must be k percent less than A. The truth of the matter is as follows: If A is k percent greater than B, then B is NOT k percent less than A. I wrote an article about this misconception: http://www.gmatprepnow.com/articles/com ... 93partii MY SOLUTION: Let x = the total BEFORE the gratuity. A 15% gratuity = 0.15x So, the TOTAL cost = x + 0.15x In other words, the TOTAL cost = 1.15x So, we can write 1.15x = 207 So, x = 207/1.15 NOTE: The GMAT often rewards people for using fractions rather than decimals. The reason for this is that most people are very uncomfortable working with fractions. So...... 207/ 1.15 = 207/ (1 3/20) [I converted the decimal to a fraction]= 207/ (23/20)= 207 x (20/23)IMPORTANT: At this point, the calculation looks very hard. But first notice that (23)(10) = 230. In other words, 230 = the sum of ten 23's Also notice that 207 is 23 less than 230 So, 207 = the sum of nine 23's In other words 207 = (23)(9)So, we have . . . = (23)(9) x (20/23)= 9 x 20 [the 23's cancel out]= 180Yes, these calculations look cumbersome, but that's only because I added a lot of extra information. In reality, students with strong fraction skills can perform most (if not all) of these calculations in their heads. Since the total PREGRATUITY price = $180, the price PER PERSON = 180/15 = 12 Answer: Cheers, Brent
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Re: The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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28 Aug 2017, 19:59
I did this as below: Given 15 people>207 cost, so avg price=13.8 including the 15%. so now we can eliminate answers c,d,e.. From a and b, just add 15% to the value and check which one becomes 13.8. Suppose you take 12, then add its 15% you get 13.8. So ans is B.



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Re: The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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09 Sep 2017, 01:30
Can be solved with equations 15*1.15x= $207 >x=207*100/15*115 > x= $12



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Re: The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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25 Sep 2017, 22:52
The simple way is no need to calculate for 15 people how much then taking avergae here 115/100 =207 again to take average we need to divide it by 15 do this operation now only So it become answer = (207*100/115*15) then solve we will get 69*4/23 ..now easily 69/23 equal to 3 so answer should be 3*4 = 12 Can be solved within 1.5 minute
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The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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23 Oct 2017, 13:30
Bunuel wrote: kashishh wrote: GyanOne wrote: The mistake you have made is that you have calculated the gratuity on the final amount, instead of finding the amount on which gratuity was charged to get the final amount.
If the amount spent excluding the gratuity was x, then x(1.15) = 207 => x = 207/1.15 = 180
Then the average price per person = 180/15 = 12
Option (B) gratuity is charged on final amount then is it not obvious to calculate such as! just wish to have clarification on the two : 1.) 270  15% of 270 = 175.95/ 15 = 11.73 2.) if 115 is 270 then 100 = 180 and 180/15 = 12 is it not the same thing ? Tip is charged on the bill. Consider this: the bill is $100 and tip is 15% means that total amount paid is 100+15=$115. The price of lunch for 15 people was $207 including a 15% gratuity for service. What was the average price per person, EXCLUDING the gratuity?A. 11.73 B. 12 C. 13.8 D. 14 E. 15.87 Bill*1.15=$207 > Bill=$180 > per person=$180/15=$12. Answer: B. Hii.. I don't get why this solution isn't the same as 0.85*207.. Would you please explain this? Thanks..



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Re: The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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23 Oct 2017, 21:13



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The price of lunch for 15 people was $207.00, including a 15 [#permalink]
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23 Oct 2017, 22:31
[quote="enigma123"]The price of lunch for 15 people was $207.00, including a 15 percent gratuity for service. What was the average price per person, EXCLUDING the gratuity?
(A) $11.73 (B) $12.00 (C) $13.80 (D) $14.00 (E) $15.87 \(Here:
207 * \frac{20}{23} * \frac{1}{15}\) =\(9 * \frac{4}{3} = 12... B\)
I think the quick way is to believe that most GMAT word problems divide smoothly and pay attention to the numbers, for example, it should be obvious that \(\frac{207}{23} = 9\) i.e \(23(101) = 9(23)= 207\)




The price of lunch for 15 people was $207.00, including a 15
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