Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 03 Apr 2006
Posts: 44

A clock store sold a certain clock to a collector for 20 per
[#permalink]
Show Tags
Updated on: 06 May 2014, 09:27
Question Stats:
77% (02:06) correct 23% (02:35) wrong based on 594 sessions
HideShow timer Statistics
A clock store sold a certain clock to a collector for 20 percent more than the store had originally paid for the clock. When the collector tried to resell the clock to the store, the store bought it back at 50 percent of what the collector had paid. The shop then sold the clock again at a profit of 80 percent on its buyback price. If the difference between the clock's original cost to the shop and the clock's buyback price was $100, for how much did the shop sell the clock the second time? A. $270 B. $250 C. $240 D. $220 E. $200
Official Answer and Stats are available only to registered users. Register/ Login.
Originally posted by hsk on 11 Jun 2007, 21:02.
Last edited by Bunuel on 06 May 2014, 09:27, edited 1 time in total.
Renamed the topic, edited the question and added the OA.




Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8196
Location: Pune, India

Re: A clock store sold a certain clock to a collector for 20 per
[#permalink]
Show Tags
06 May 2014, 20:22
hsk wrote: A clock store sold a certain clock to a collector for 20 percent more than the store had originally paid for the clock. When the collector tried to resell the clock to the store, the store bought it back at 50 percent of what the collector had paid. The shop then sold the clock again at a profit of 80 percent on its buyback price. If the difference between the clock's original cost to the shop and the clock's buyback price was $100, for how much did the shop sell the clock the second time?
A. $270 B. $250 C. $240 D. $220 E. $200 Assume numbers and then use ratios to fit them in with the actual numbers. Say the store bought the clock for $100 and sold it to the collector for $120. The store bought back from the collector for $60 and sold it back at $60*18/10 = $108 Here, difference between original cost ($100) and buy back price ($60) is $40. But actually it is given to be $100 which is 2.5 times 40. So the shop sold the clock a second time for $108*2.5 = $270
_________________
Karishma Veritas Prep GMAT Instructor
Save up to $1,000 on GMAT prep through 8/20! Learn more here >
GMAT selfstudy has never been more personalized or more fun. Try ORION Free!




Senior Manager
Joined: 04 Jun 2007
Posts: 341

$270
Original Price = x
Sold to collector at 1.2x
rebuy price = 1.2x * 0.5 = 0.6x
therefore, x  0.6x = 100; x = 250
second selling price = 1.8 * 0.6 * 250 = 270
Hope, this is not too confusing




Senior Manager
Joined: 04 Mar 2007
Posts: 419

100 %  original price
120 %  sell 1
60 %  bought 2
180*60/100 = 108 %  sell 2
100$  40%
x  108 %
x= 100*108/40 = 270
A



eGMAT Representative
Joined: 04 Jan 2015
Posts: 1900

Re: A clock store sold a certain clock to a collector for 20 per
[#permalink]
Show Tags
02 Jun 2015, 00:44
The question is a bit wordy and gives us a series of percentages on which we need to work on. Going step wise is the key to not miss out on any of the information. Presenting the detailed step wise solution StepI Store buys the clockLet's assume the original price of clock paid by the store to be \(x\) StepII Collectors buys the clock from the storeExtra amount paid by collector to buy the clock = \(20\)% of \(x\) Therefore price at which collector buys the clock = \(x + 20\)% of \(x = 1.2x\) StepIII Store buys back the clock from collectorPrice at which the store buys the clock = \(50\)% of price collector paid \(= 50\)% of \(1.2x = 0.6x\) StepIV Store resells the clockPrice at which store resells the clock = \(0.6x + 80\)% of \(0.6x = 0.6x * 1.8\) Now, we are given that difference between clock's original price and clock's buy back price = \(100\) \(x  0.6x = 100\) i.e. \(x = 250\) We are asked to find the price at which the store resells the clock = \(0.6x * 1.8 = 0.6 * 250 * 1.8 = 270\) Hope this helps Regards Harsh
_________________
Register for free sessions Number Properties  Algebra Quant Workshop
Success Stories Guillermo's Success Story  Carrie's Success Story
Ace GMAT quant Articles and Question to reach Q51  Question of the week
Must Read Articles Number Properties – Even Odd  LCM GCD Word Problems – Percentage 1  Percentage 2  Time and Work 1  Time and Work 2  Time, Speed and Distance 1  Time, Speed and Distance 2 Advanced Topics Permutation and Combination 1  Permutation and Combination 2  Permutation and Combination 3  Probability Geometry Triangles 1  Triangles 2  Triangles 3  Common Mistakes in Geometry Algebra Wavy line Practice Questions Number Properties 1  Number Properties 2  Algebra 1  Geometry  Prime Numbers  Absolute value equations  Sets
 '4 out of Top 5' Instructors on gmatclub  70 point improvement guarantee  www.egmat.com



Intern
Joined: 25 Dec 2012
Posts: 17

Re: A clock store sold a certain clock to a collector for 20 per
[#permalink]
Show Tags
11 Jul 2015, 13:39
EgmatQuantExpert wrote: The question is a bit wordy and gives us a series of percentages on which we need to work on. Going step wise is the key to not miss out on any of the information. Presenting the detailed step wise solution StepI Store buys the clockLet's assume the original price of clock paid by the store to be \(x\) StepII Collectors buys the clock from the storeExtra amount paid by collector to buy the clock = \(20\)% of \(x\) Therefore price at which collector buys the clock = \(x + 20\)% of \(x = 1.2x\) StepIII Store buys back the clock from collectorPrice at which the store buys the clock = \(50\)% of price collector paid \(= 50\)% of \(1.2x = 0.6x\) StepIV Store resells the clockPrice at which store resells the clock = \(0.6x + 80\)% of \(0.6x = 0.6x * 1.8\) Now, we are given that difference between clock's original price and clock's buy back price = \(100\) \(x  0.6x = 100\) i.e. \(x = 250\) We are asked to find the price at which the store resells the clock = \(0.6x * 1.8 = 0.6 * 250 * 1.8 = 270\) Hope this helps Regards Harsh Dear, I have a basic question. The author states: "The shop then sold the clock again at a profit of 80 percent on its buyback price". Why is it suppose to multiply 0.6x*1.8? I think my confuse is related to the profit concept. For me, if I buy something at 100, and the cost of it is 80. I have a profit of 20/100 = 20%. Using the same logic on the question, if I buy something at 100 and I get a profit of 80%, the sales price must be 100/0.2. Thus, it is 500. Profit is 400/500=80%. It is a totally different aproach than to say 100*1,8. Where my confuse is? Kind regards... Gonzalo



Current Student
Joined: 20 Mar 2014
Posts: 2643
Concentration: Finance, Strategy
GPA: 3.7
WE: Engineering (Aerospace and Defense)

Re: A clock store sold a certain clock to a collector for 20 per
[#permalink]
Show Tags
11 Jul 2015, 13:54
gbascurs wrote: EgmatQuantExpert wrote: The question is a bit wordy and gives us a series of percentages on which we need to work on. Going step wise is the key to not miss out on any of the information. Presenting the detailed step wise solution StepI Store buys the clockLet's assume the original price of clock paid by the store to be \(x\) StepII Collectors buys the clock from the storeExtra amount paid by collector to buy the clock = \(20\)% of \(x\) Therefore price at which collector buys the clock = \(x + 20\)% of \(x = 1.2x\) StepIII Store buys back the clock from collectorPrice at which the store buys the clock = \(50\)% of price collector paid \(= 50\)% of \(1.2x = 0.6x\) StepIV Store resells the clockPrice at which store resells the clock = \(0.6x + 80\)% of \(0.6x = 0.6x * 1.8\) Now, we are given that difference between clock's original price and clock's buy back price = \(100\) \(x  0.6x = 100\) i.e. \(x = 250\) We are asked to find the price at which the store resells the clock = \(0.6x * 1.8 = 0.6 * 250 * 1.8 = 270\) Hope this helps Regards Harsh Dear, I have a basic question. The author states: "The shop then sold the clock again at a profit of 80 percent on its buyback price". Why is it suppose to multiply 0.6x*1.8? I think my confuse is related to the profit concept. For me, if I buy something at 100, and the cost of it is 80. I have a profit of 20/100 = 20%. Using the same logic on the question, if I buy something at 100 and I get a profit of 80%, the sales price must be 100/0.2. Thus, it is 500. Profit is 400/500=80%. It is a totally different aproach than to say 100*1,8. Where my confuse is? Kind regards... Gonzalo Gonzalo, Profit is calculated = Selling price  Cost price. Profit % is always calculated on the cost price of the purchase and not on the selling price. You are calculating profit % on the selling price. This is where you are going wrong. I am assuming that in your example, you are buying something at 80 while you are selling it at 100, giving you an absolute profit of 20$ while your profit % will be 20/80 = 25% and not 20/100 = 20%. Now, in the question above, lets say the original cost of the clock to store was C$ and then it sold the same to the collector at 20% profit. This means the clocks' selling price was C (1.2) and this becomes cost price for the collector. Now, when the collector tries to sell the same clock to the store, the store buys it for 50% the price at which the collector bought it. Thus, you get = 1.2*0.5*C = 0.6 C Furthermore, the store sells the clock for the second time for 80% profit and thus the selling price of the clock becomes = cost price of the clock for the store at buyback * 1.8 = 1.8 * 0.6 C Finally given that C  0.6 C = 100 > C = 250$ Thus, the cost of the clock the second time around = 1.8*0.6 C = 1.8 * 0.6 * 250 = 270$. Hence A is the correct answer.



Intern
Joined: 25 Dec 2012
Posts: 17

Re: A clock store sold a certain clock to a collector for 20 per
[#permalink]
Show Tags
11 Jul 2015, 14:20
Engr2012 wrote: gbascurs wrote: EgmatQuantExpert wrote: The question is a bit wordy and gives us a series of percentages on which we need to work on. Going step wise is the key to not miss out on any of the information. Presenting the detailed step wise solution StepI Store buys the clockLet's assume the original price of clock paid by the store to be \(x\) StepII Collectors buys the clock from the storeExtra amount paid by collector to buy the clock = \(20\)% of \(x\) Therefore price at which collector buys the clock = \(x + 20\)% of \(x = 1.2x\) StepIII Store buys back the clock from collectorPrice at which the store buys the clock = \(50\)% of price collector paid \(= 50\)% of \(1.2x = 0.6x\) StepIV Store resells the clockPrice at which store resells the clock = \(0.6x + 80\)% of \(0.6x = 0.6x * 1.8\) Now, we are given that difference between clock's original price and clock's buy back price = \(100\) \(x  0.6x = 100\) i.e. \(x = 250\) We are asked to find the price at which the store resells the clock = \(0.6x * 1.8 = 0.6 * 250 * 1.8 = 270\) Hope this helps Regards Harsh Dear, I have a basic question. The author states: "The shop then sold the clock again at a profit of 80 percent on its buyback price". Why is it suppose to multiply 0.6x*1.8? I think my confuse is related to the profit concept. For me, if I buy something at 100, and the cost of it is 80. I have a profit of 20/100 = 20%. Using the same logic on the question, if I buy something at 100 and I get a profit of 80%, the sales price must be 100/0.2. Thus, it is 500. Profit is 400/500=80%. It is a totally different aproach than to say 100*1,8. Where my confuse is? Kind regards... Gonzalo Gonzalo, Profit is calculated = Selling price  Cost price. Profit % is always calculated on the cost price of the purchase and not on the selling price. You are calculating profit % on the selling price. This is where you are going wrong. I am assuming that in your example, you are buying something at 80 while you are selling it at 100, giving you an absolute profit of 20$ while your profit % will be 20/80 = 25% and not 20/100 = 20%. Now, in the question above, lets say the original cost of the clock to store was C$ and then it sold the same to the collector at 20% profit. This means the clocks' selling price was C (1.2) and this becomes cost price for the collector. Now, when the collector tries to sell the same clock to the store, the store buys it for 50% the price at which the collector bought it. Thus, you get = 1.2*0.5*C = 0.6 C Furthermore, the store sells the clock for the second time for 80% profit and thus the selling price of the clock becomes = cost price of the clock for the store at buyback * 1.8 = 1.8 * 0.6 C Finally given that C  0.6 C = 100 > C = 250$ Thus, the cost of the clock the second time around = 1.8*0.6 C = 1.8 * 0.6 * 250 = 270$. Hence A is the correct answer. Thank you a lot. Here is the key of my misunderstanding: "Profit % is always calculated on the cost price of the purchase". I assumed it was on the sales price.



Intern
Joined: 08 Oct 2014
Posts: 9
GPA: 4

A clock store sold a certain clock to a collector for 20 per
[#permalink]
Show Tags
10 Nov 2015, 05:00
x=starting price therefore x +20% = \(x +1/5x\) = \(6x/5\) 50% = 3x/5 BB Price as per Q x  \(3x/5\)=100 x=250 BB =150 80 %increment of 150 = 270
_________________
urban hermit



Senior Manager
Joined: 20 Aug 2015
Posts: 392
Location: India

A clock store sold a certain clock to a collector for 20 per
[#permalink]
Show Tags
10 Nov 2015, 05:20
hsk wrote: A clock store sold a certain clock to a collector for 20 percent more than the store had originally paid for the clock. When the collector tried to resell the clock to the store, the store bought it back at 50 percent of what the collector had paid. The shop then sold the clock again at a profit of 80 percent on its buyback price. If the difference between the clock's original cost to the shop and the clock's buyback price was $100, for how much did the shop sell the clock the second time?
A. $270 B. $250 C. $240 D. $220 E. $200 Let us assume the initial price (CP) of the clock to be 100x We assume 100x to avoid the usage of decimals in case of x and avoid the usage of unitary method in case of 100Transaction 1: Store sold the clock to collector. Selling Price = 20% more than CP = 120x Transaction 2: The collector sold it back to the store. The new CP for the store = 60x (Store bought it back for 50% of the Selling Price) Transaction 3: Store sold it back at a profit of 80% on 60x = 108x Now we are told that 100x  60x = 100 This means x = 100/40 Hence the second selling price = 108*100/40 = 270 Option A



NonHuman User
Joined: 09 Sep 2013
Posts: 7774

Re: A clock store sold a certain clock to a collector for 20 per
[#permalink]
Show Tags
11 Feb 2018, 00:34
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). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: A clock store sold a certain clock to a collector for 20 per &nbs
[#permalink]
11 Feb 2018, 00:34






