Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 16 Apr 2018
Posts: 1

Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
12 Dec 2018, 09:39
Hi experts, i understand the above mentioned approach but could you please tell me why is the following approach wrong
Let 'x' be the number of Apples, 'y' be the number of Oranges so x+y=10 Since the average (i.e., price of fruits/ the the total number of fruits) is 56 (40x + 60y)/10 = 56 On solving x=2 and y =8
Now the question states that the adjusted average is 52 So (40x + 60y)/10 = 52 On solving x=4 and y=6
So if Mary picks up 8 Oranges the average is 56 but if she picks up 6 Oranges the average drops to 52 Clearly she has to drop 2 Oranges to acquire the desired average.



Intern
Joined: 28 Apr 2016
Posts: 43
Location: United States
GMAT 1: 780 Q51 V47
GPA: 3.9

Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
12 Dec 2018, 09:49
AkhilRao wrote: Hi experts, i understand the above mentioned approach but could you please tell me why is the following approach wrong
Let 'x' be the number of Apples, 'y' be the number of Oranges so x+y=10 Since the average (i.e., price of fruits/ the the total number of fruits) is 56 (40x + 60y)/10 = 56 On solving x=2 and y =8
Now the question states that the adjusted average is 52 So (40x + 60y)/10 = 52 On solving x=4 and y=6
So if Mary picks up 8 Oranges the average is 56 but if she picks up 6 Oranges the average drops to 52 Clearly she has to drop 2 Oranges to acquire the desired average. Sure! Your approach would be correct if the question asked about how many oranges she would need to exchange for apples in order to have the average price be 52 cents. In that case, the number of fruits would remain 10, and 6 oranges/4 apples would give an average price of 52 cents. However, the question asks how many oranges she must put back, so all she can do is reduce the number of oranges; she cannot increase the number of apples. So, the number of apples must remain 2, and we need to know how many oranges she will need to have in order for the average price to be 52 cents. This is 3 oranges, so she needs to put back 5 oranges to go from having 8 oranges/2 apples to having 3 oranges/2 apples. Please let me know if you have more questions!
_________________
Online GMAT tutor with a 780 GMAT score. Harvard graduate. Please read and share my free GMAT Timing Strategy Guide!



GMAT Club Legend
Joined: 11 Sep 2015
Posts: 4879
Location: Canada

Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
11 Jan 2019, 09:39
Bunuel wrote: At a certain fruit stand, the price of each apple is 40 cents and the price of each orange is 60 cents. Mary selects a total of 10 apples and oranges from the fruit stand, and the average (arithmetic mean) price of the 10 pieces of fruit is 56 cents. How many oranges must Mary put back so that the average price of the pieces of fruit that she keeps is 52 cents?
(A) 1 (B) 2 (C) 3 (D) 4 (E) 5
Kudos for a correct solution. It turns out that the cost per apple is irrelevant. Here's why: The average (arithmetic mean) price of the 10 pieces of fruit is 56 centsSo, (total value of all 10 pieces of fruit)/10 = 56 cents This means, total value of all 10 pieces of fruit = 560 cents How many oranges must Mary put back so that the average price of the pieces of fruit that she keeps is 52 cents?Let x = the number of oranges to be removed. Each orange costs 60 cents, so the value of the x oranges to be removed = 60x This means 560  60x = the value of the REMAINING fruit Also, if we remove x oranges, then 10  x = the number of pieces of fruit REMAINING. We want the REMAINING fruit to have an average value of 52 cents. We can write: (value of REMAINING fruit)/(number of pieces of fruit REMAINING) = 52 Rewrite as: ( 560  60x)/( 10  x) = 52 Multiply both sides by (10x) to get: 560  60x = 52(10  x) Expand right side to get: 560  60x = 520  52x Add 60x to both sides: 560 = 520 + 8x Subtract 520 from both sides: 40 = 8x Solve: x = 5 Answer: E Cheers, Brent
_________________
Test confidently with gmatprepnow.com



Manager
Joined: 16 Jul 2016
Posts: 52

Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
26 Jan 2019, 13:13
This can be done very quickly using weighted average principles.
since the average ends up being 52 cents.
40 60 52
(6052) (5240)
8/12=2/3. So the number of apples is 2x and the number of oranges is 3x. The sum has to be a multiple of 5. After some number of oranges were removed there must have been 5 left. Therefore, he must have removed 5 oranges.



VP
Joined: 14 Feb 2017
Posts: 1369
Location: Australia
Concentration: Technology, Strategy
GMAT 1: 560 Q41 V26 GMAT 2: 550 Q43 V23 GMAT 3: 650 Q47 V33 GMAT 4: 650 Q44 V36 GMAT 5: 650 Q48 V31 GMAT 6: 600 Q38 V35 GMAT 7: 710 Q47 V41
GPA: 3
WE: Management Consulting (Consulting)

Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
10 May 2019, 16:23
Here's an easy way to solve this: Let A = apples, B = oranges (40A + 60B)/10 = 56 (40A +60 (10A))/10 = 56 40A + 600  60A = 560 20A = 40 A = 2 Therefore, B = 8 So, how many of the 8 oranges do we need to remove to bring down the average? let x = the number of oranges we need to remove (40*(2apples) + 60 (8x) )/10x = 52 80+480 60x = 520  52x 560 =520+8x 40= 8x x = 5 (E)
_________________
Here's how I went from 430 to 710, and how you can do it yourself: https://www.youtube.com/watch?v=KGY5vxqMeYk&t=



Intern
Joined: 17 Feb 2019
Posts: 27
Location: India
GMAT 1: 610 Q43 V31

Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
05 Sep 2019, 04:51
v12345 wrote: Bunuel wrote: At a certain fruit stand, the price of each apple is 40 cents and the price of each orange is 60 cents. Mary selects a total of 10 apples and oranges from the fruit stand, and the average (arithmetic mean) price of the 10 pieces of fruit is 56 cents. How many oranges must Mary put back so that the average price of the pieces of fruit that she keeps is 52 cents?
(A) 1 (B) 2 (C) 3 (D) 4 (E) 5
Kudos for a correct solution. here price of apple = 40 cents and price of orange = 60 cents average price = 56 cents so, the apples and oranges are in ratio apple : orange = 60  56 : 56  40 => apple : orange = 4 : 16 => apple : orange = 1 : 4 total no =10, therefore apples = 2 nos. and oranges = 8 nos. now we have to make average price = 52 centsso, the apples and oranges will be in ratio apple : orange = 60  52 : 52  40 => apple : orange = 8 : 12 => apple : orange = 2 : 3 now we have apples = 2 nos. from above, therefore oranges must be 3 in number oranges to be put back = 8  3 = 5 nosAnswer choice Ekudos if you like the explanation Why did you assume, in the second ratio, 2:3, that the total apples is 2 and oranges is 3? You are not given total, as in the first ratio (where total given is 10). Here, total is less than 10, but you don't know what.



Manager
Joined: 03 Aug 2017
Posts: 100

At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
07 Oct 2019, 04:03
Bunuel wrote: At a certain fruit stand, the price of each apple is 40 cents and the price of each orange is 60 cents. Mary selects a total of 10 apples and oranges from the fruit stand, and the average (arithmetic mean) price of the 10 pieces of fruit is 56 cents. How many oranges must Mary put back so that the average price of the pieces of fruit that she keeps is 52 cents?
(A) 1 (B) 2 (C) 3 (D) 4 (E) 5
Kudos for a correct solution. Hello Bunuel, I have a very basic doubt.. In one of the solutions it is given apple : orange = 60  56 : 56  40 => apple : orange = 4 : 16 => apple : orange = 1 : 4 I want to know how the ratio of Apple is 4 And Oranges 16? How did we arrive at this? For your help i have pasted one of the answers below from where this is taken " here price of apple = 40 cents and price of orange = 60 cents average price = 56 cents so, the apples and oranges are in ratio apple : orange = 60  56 : 56  40 => apple : orange = 4 : 16 => apple : orange = 1 : 4 total no =10, therefore apples = 2 nos. and oranges = 8 nos. now we have to make average price = 52 cents so, the apples and oranges will be in ratio apple : orange = 60  52 : 52  40 => apple : orange = 8 : 12 => apple : orange = 2 : 3 now we have apples = 2 nos. from above, therefore oranges must be 3 in number oranges to be put back = 8  3 = 5 nos Answer choice E



Intern
Joined: 10 Jul 2018
Posts: 5

Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
08 Oct 2019, 01:42
As is given in the quwstion 60x + 40y = 56*10 And x+y = 10 Thus x = 8 and y = 2 Now, 60p + 40*2 = 52 (p+2) 8p = 104 80 thus p = 3 So the number of orange is to be reduced by 5 =(83) OA: E
Posted from my mobile device



Intern
Joined: 26 May 2019
Posts: 24
Location: India

Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
17 Oct 2019, 02:09
There is a much simpler approach to this problem. We do not require any use of weighted averages or ratios or any other complex calculations. This sum can be solved within 1025sec, after reading the question.
40a+60o = 560 (average of 10 fruits is 56)
a + o = 10
40a + 60(ox) = 52(10x) (Since the new average is 52)
We can see from the left side of the equation that the total price is a multiple of 10. This is possible only if 10x = 10 or 5. 10 can be eliminated because we have to return some oranges. There is only 1 value of x for which 52 will be a multiple of 10, which is 5.
Solved only with common sense.



Intern
Joined: 03 Dec 2019
Posts: 23

Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
07 Dec 2019, 06:28
Confusing question. I read it as if Mary would always select a total of 10 apples and oranges; so that if an orange is removed, it must be replaced with an apple (as if the total must always be 10). Doing this would result in answer B (2); she would replace 2 oranges with 2 apples resulting in a total price of 520 cents.
If Mary only removes, and not replaces, oranges (thus the total number of fruit does not have to be 10), than the correct answer would be E.



Senior Manager
Joined: 21 Feb 2017
Posts: 478

Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
Show Tags
08 Mar 2020, 10:06
Bunuel wrote: At a certain fruit stand, the price of each apple is 40 cents and the price of each orange is 60 cents. Mary selects a total of 10 apples and oranges from the fruit stand, and the average (arithmetic mean) price of the 10 pieces of fruit is 56 cents. How many oranges must Mary put back so that the average price of the pieces of fruit that she keeps is 52 cents?
(A) 1 (B) 2 (C) 3 (D) 4 (E) 5
Kudos for a correct solution. IMO, an easier method by trying out answer choices. Average = Total sum/number of items => Sum/10=56, therefore, the sum of 10 A and O = 560 Start with answer choice C: if she puts back 3 oranges, then the sum will reduce by 60*3=180; new average = 560180/7 => 54.2 not our answer as average needs to be 52 ( we divide by 7 as now after taking 3 oranges out, only 7 fruits would be left) By trial and error, you will see for answer choice E when she takes out five oranges sum reduces by 5*60 (300) therefore 260/5 = 52 our answer!




Re: At a certain fruit stand, the price of each apple is 40 cents and the
[#permalink]
08 Mar 2020, 10:06



Go to page
Previous
1 2
[ 31 posts ]

