GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 15 Nov 2019, 06:02 ### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  # The number of stamps that Kaye and Alberto had were in the

Author Message
TAGS:

### Hide Tags

Board of Directors D
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4831
Location: India
GPA: 3.5
Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

2
kilukilam wrote:
The number of stamps that Kaye and Alberto had were in the ration of 5:3 respecctively. After Kaye gave Alberto 10 of her stamps, the ration of the number of Kaye had to the number of Alberto had was 7:5. As a result of the gift, Kaye had how many more stamps than Alberto

A. 20
B. 30
C. 40
D. 60
E. 90

Lets work -
Quote:
The number of stamps that Kaye and Alberto had were in the ration of 5:3 respectively.

Attachment: 1.PNG [ 1.09 KiB | Viewed 1912 times ]

Quote:
After Kaye gave Alberto 10 of her stamps, the ration of the number of Kaye had to the number of Alberto had was 7:5.

Attachment: 2.PNG [ 1.48 KiB | Viewed 1911 times ]

So, $$\frac{(5x-10)}{(3x+10)} = \frac{7}{5}$$

Or, $$25x - 50 = 21x + 70$$

Or, $$4x = 120$$

Or, $$x = 30$$

We are asked to find -
Quote:
As a result of the gift, Kaye had how many more stamps than Alberto

Or, (5x-10) - (3x+10) => 2x - 20

Or, 2(30) - 20 =40

_________________
Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )
VP  P
Joined: 07 Dec 2014
Posts: 1220
Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

The number of stamps that Kaye and Alberto had were in the ratio of 5:3 respectively. After Kaye gave Alberto 10 of her stamps,
the ratio of the number Kaye had to the number Alberto had was 7:5. As a result of the gift, Kaye had how many more stamps than Alberto?

A. 20
B. 30
C. 40
D. 60
E. 90

let x=total stamps
5/8*x-10=7/12*x
x=240
7/12*240=140
5/12*240=100
140-100=40
C.
Target Test Prep Representative V
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8381
Location: United States (CA)
Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

kilukilam wrote:
The number of stamps that Kaye and Alberto had were in the ration of 5:3 respecctively. After Kaye gave Alberto 10 of her stamps, the ration of the number of Kaye had to the number of Alberto had was 7:5. As a result of the gift, Kaye had how many more stamps than Alberto

A. 20
B. 30
C. 40
D. 60
E. 90

We are given that the number of stamps that Kaye and Alberto had were in the ratio 5 : 3. We can represent this as:

K : A = 5x : 3x

We are next given that after Kaye gave Alberto 10 of her stamps, the ratio of the number Kaye had to the number Alberto had was 7 : 5. Using this information we can create the following equation:

(5x – 10)/(3x + 10)= 7/5

5(5x – 10) = 7(3x + 10)

25x – 50 = 21x + 70

4x = 120

x = 30

Kaye now has 5(30) – 10 = 140 stamps and Alberto has 3(30) + 10 = 100 stamps. So Kaye has 140 – 100 = 40 more stamps than Alberto.

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Manager  S
Joined: 03 Jan 2017
Posts: 134
Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

this is a very very very! tricky question,
to avoid the trick I advise to write down from the beginning what the question asks, and this is: (5x-10)-(3x+10)

let's make up an equation:
(5x-10)/(3x+10)=7/5
we will find that x=30
Let's put it into the required formula above: (5*30-10)-(3*30+10)=40
be careful not to use ration 7:5, because it has no relation to x
this is where the whole trick is

Manager  G
Status: Not Applying
Joined: 27 Apr 2009
Posts: 178
Location: India
Schools: HBS '14 (A)
GMAT 1: 730 Q51 V36 Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

The number of stamps that Kaye and Alberto had were in the ration of 5:3 respecctively. After Kaye gave Alberto 10 of her stamps, the ration of the number of Kaye had to the number of Alberto had was 7:5. As a result of the gift, Kaye had how many more stamps than Alberto

A. 20
B. 30
C. 40
D. 60
E. 90

Solution: Let Kaye has 5x stamps and Alberto has 3x stamps. (5x:3x = 5:3)
When Kaye gives 10 stamps, he is left with (5x - 10) stamps.
and because Alebrto gets 10 stamps, he now has (3x + 10) stamps.
The new ratio is given as 7:5
=> (5x - 10)/((3x + 10) = 7/5
=> 5*(5x - 10) = 7*(3x + 10)
=> 25x - 50 = 21x + 70
=> 25x - 21x = 70 + 50
=> 4x = 120
=> x = 30
Don't be tempted to mark this as your answer. The question is asking something different. The question wants you to find the value of (5x - 10) - (3x + 10)

(5x - 10) - (3x + 10) = 2x - 20 = (2*30) - 20 = 60 - 20 = 40

_________________
http://www.wizius.in
Better Prep. Better Scores. Better Schools

Guaranteed Admission to Top-50 MBA Programs
You either get-in or get your money-back.
Manager  B
Joined: 23 Dec 2013
Posts: 138
Location: United States (CA)
GMAT 1: 710 Q45 V41 GMAT 2: 760 Q49 V44 GPA: 3.76
Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

kilukilam wrote:
The number of stamps that Kaye and Alberto had were in the ration of 5:3 respecctively. After Kaye gave Alberto 10 of her stamps, the ration of the number of Kaye had to the number of Alberto had was 7:5. As a result of the gift, Kaye had how many more stamps than Alberto

A. 20
B. 30
C. 40
D. 60
E. 90

(5x - 10 )/ (3x + 10) = 7x/5x

(5x - 10)*5 = 7(3x+10)

25x - 50 = 21x + 70
4x = 120
x = 30

Now we need to find the final values after the trade occurs.

K: 5(30) - 10 = 150-10 = 140

A: 3(30) + 10 = 100

140 - 100 = 40.
Manager  S
Joined: 23 Jan 2016
Posts: 180
Location: India
GPA: 3.2
Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

Bunuel, could you explain whats wrong with the the following method?

x/y =3/5. x-10/y+10 = 7/5. Hence on solving we get x as 50 and y as 30, which clearly does not tell us the answer. Can you please provide some conceptual clarity?
Senior Manager  B
Joined: 28 Jun 2015
Posts: 281
Concentration: Finance
GPA: 3.5
Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

kilukilam wrote:
The number of stamps that Kaye and Alberto had were in the ration of 5:3 respecctively. After Kaye gave Alberto 10 of her stamps, the ration of the number of Kaye had to the number of Alberto had was 7:5. As a result of the gift, Kaye had how many more stamps than Alberto

A. 20
B. 30
C. 40
D. 60
E. 90

$$\frac{K}{A} = \frac{5x}{3x}$$

$$\frac{5x-10}{3x+10} = \frac{7}{5}$$

$$25x - 50 = 21x + 70$$
$$4x = 120$$
$$x = 30$$

$$A = 3(30)+10 = 100$$
$$K = 5(30)-10 = 140$$

$$K-A = 40$$. Ans - C.
_________________
I used to think the brain was the most important organ. Then I thought, look what’s telling me that.
Senior Manager  B
Joined: 28 Jun 2015
Posts: 281
Concentration: Finance
GPA: 3.5
Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

1
OreoShake wrote:
Bunuel, could you explain whats wrong with the the following method?

x/y =3/5. x-10/y+10 = 7/5. Hence on solving we get x as 50 and y as 30, which clearly does not tell us the answer. Can you please provide some conceptual clarity?

Hi, there are a couple of things to note here.

I'm assuming that you assigned the variables x and y as: Alberto = x, Kaye = y. First off, when two things are in a ratio they must be represented using a common variable, if there were no relationship mentioned, for instance if it says that Kaye and Alberto had some stamps, then you may assign two separate variables to each since we don't know in what way they are related, if at all.

Secondly, Kaye gave Alberto 10 stamps, so it must be x+10/y-10 = 7/5. This equation cannot be solved for x and y, one value has to be represented using the other, since there are 2 variables involved.
_________________
I used to think the brain was the most important organ. Then I thought, look what’s telling me that.
Target Test Prep Representative G
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2812
Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

kilukilam wrote:
The number of stamps that Kaye and Alberto had were in the ration of 5:3 respecctively. After Kaye gave Alberto 10 of her stamps, the ration of the number of Kaye had to the number of Alberto had was 7:5. As a result of the gift, Kaye had how many more stamps than Alberto

A. 20
B. 30
C. 40
D. 60
E. 90

We are given that the number of stamps that Kaye and Alberto had was in the ratio 5 : 3. We can represent this as:

K : A = 5x : 3x

We are next given that after Kaye gave Alberto 10 of her stamps, the ratio of the number Kaye had to the number Alberto had was 7 : 5. Using this information, we can create the following equation:

(5x – 10)/(3x + 10) = 7/5

5(5x – 10) = 7(3x + 10)

25x – 50 = 21x + 70

4x = 120

x = 30

Kaye now has 5(30) – 10 = 140 stamps, and Alberto has 3(30) + 10 = 100 stamps. So Kaye has 140 – 100 = 40 more stamps than Alberto has.

_________________

# Jeffrey Miller

Jeff@TargetTestPrep.com

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

CrackVerbal Quant Expert G
Joined: 12 Apr 2019
Posts: 274
Re: The number of stamps that Kaye and Alberto had were in the  [#permalink]

### Show Tags

This is a fairly easy question on ratios, but with a big trap in terms of language. The most common answer that a lot of students get on this question is 60 i.e. option D. However, this is the trap answer.

Questions like these on ratios test your knowledge of mutliples of numbers. As such, although the conventional approach of assuming the stamps as 5x and 3x and then building an equation followed by solving the equation yields you the answer, it’s always good to approach ratio questions using numbers.

We know that the number of stamps that Kaye and Alberto had are multiples of 5 and 3 respectively. So, what do we do? Do we start with 5 and 3? The answer is a bigg no. Observe the options, all the options are bigger numbers than 5 and 3. And remember that we are trying to find the difference between the number of stamps. We need to take bigger multiples of 5 and 3, which are multiples of 10 as well (preferably).

Let’s try 50 and 30, then. After gifting 10 stamps to Alberto, the respective numbers with Kaye and Alberto would be 40 and 40. This is not in the ratio of 7:5. So, 50 and 30 are not the number of stamps.

If we try 100 and 60, we obtain the numbers 90 and 70 after the gifting process. This is in the ratio of 9:7, NOT 7:5.

When we try 150 and 90, we see that the resultant numbers after Kaye gifts alberto would be 140 and 100 which are in the ratio of 7:5. Therefore, Kaye must have started off with 150 stamps and Alberto with 90 stamps. So, Kaye had 60 more stamps than Alberto?? No, that’s not correct.

Observe that the question mentions “As a result of the gift…”. This means, we need to find out how much more Kaye had AFTER gifting 10 stamps to Alberto. AFTER gifting 10 stamps to Alberto, Kaye had 140 and Alberto had 100, so Kaye had 40 more stamps.

The correct answer option is C.

Every word, every phrase and every sentence in a GMAT question is valuable. If you rush through the questions without paying due attention, you run the risk of falling for the trap answers. If required, after you compute an answer, re-read the question statement and satisfy yourselves that you have indeed answered the actual question and NOT what you thought the question was.

Hope that helps!
_________________ Re: The number of stamps that Kaye and Alberto had were in the   [#permalink] 13 Oct 2019, 05:19

Go to page   Previous    1   2   [ 31 posts ]

Display posts from previous: Sort by

# The number of stamps that Kaye and Alberto had were in the  