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

It is currently 16 Aug 2018, 10:57

Close

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
Your Progress

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.

Close

Request Expert Reply

Confirm Cancel

At a given time, what was the ratio of the number of sailboats to the

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47945
At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 20 Dec 2015, 06:21
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

79% (01:02) correct 21% (01:09) wrong based on 165 sessions

HideShow timer Statistics

At a given time, what was the ratio of the number of sailboats to the number of motorboats on Lake X?

(1) If the number of motorboats on Lake X had been 25% greater, the number of sailboats on Lake X would have been 110% of the number of motorboats on Lake X.
(2) The positive difference between the number of motorboats on Lake X and the number of sailboats on Lake X was 30.

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Verbal Forum Moderator
User avatar
V
Status: Greatness begins beyond your comfort zone
Joined: 08 Dec 2013
Posts: 2105
Location: India
Concentration: General Management, Strategy
Schools: Kelley '20, ISB '19
GPA: 3.2
WE: Information Technology (Consulting)
GMAT ToolKit User Reviews Badge CAT Tests
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 20 Dec 2015, 07:06
1
Let the number of sailboats =s
number of motorboats = m
(1) If the number of motorboats on Lake X had been 25% greater, the number of sailboats on Lake X would have been 110% of the number of motorboats on Lake X.
1.25m = 1.1s
=>(5/4) m = (11/10)s
=> s/m = 50/44 = 25/22
Sufficient

(2) The positive difference between the number of motorboats on Lake X and the number of sailboats on Lake X was 30
s-m = 30 or m-s = 30
Not sufficient

Answer A
_________________

When everything seems to be going against you, remember that the airplane takes off against the wind, not with it. - Henry Ford
The Moment You Think About Giving Up, Think Of The Reason Why You Held On So Long
+1 Kudos if you find this post helpful

Intern
Intern
User avatar
Joined: 01 Nov 2015
Posts: 37
Location: India
Concentration: Marketing, Entrepreneurship
WE: Engineering (Computer Software)
Premium Member
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 23 Dec 2015, 00:27
Skywalker, I can understand the logic you used, but aren't we not allowed to equate sailboats and motorboats to each other?

If s was the initial no^ of sailboats and m was the initial number of motorboats, then, in the original equation, there is no relation given between then^

so, if we assume s#=5/4 s and m#=11/10 m, then #m#s#/m#= (5/4) s / (11/10) m => s# / m# =25s/22m => s/m = 22s#/25m# or 22/25 s#/m#[/m]
and in this case, the value of s/m will depend on s#/m# and hence statement I shouldn't be sufficient.

Is this assumption wrong?
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 6533
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 23 Dec 2015, 01:32
appsy01 wrote:
Skywalker, I can understand the logic you used, but aren't we not allowed to equate sailboats and motorboats to each other?

If s was the initial no^ of sailboats and m was the initial number of motorboats, then, in the original equation, there is no relation given between then^

so, if we assume s#=5/4 s and m#=11/10 m, then #m#s#/m#= (5/4) s / (11/10) m => s# / m# =25s/22m => s/m = 22s#/25m# or 22/25 s#/m#[/m]
and in this case, the value of s/m will depend on s#/m# and hence statement I shouldn't be sufficient.

Is this assumption wrong?


hi,
you are correct prior to the coloured portion..
why are you taking ratio of s# and m#.... its not correct
what we require to do is equate both of them due to the statement
If the number of motorboats on Lake X had been 25% greater, the number of sailboats on Lake X would have been 110% of the number of motorboats on Lake X...
so here s#=m#..
or (5/4) s =(11/10) m .... get s and m on one side and you will have s/m and other side you will have the ratio
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

Intern
Intern
User avatar
Joined: 01 Nov 2015
Posts: 37
Location: India
Concentration: Marketing, Entrepreneurship
WE: Engineering (Computer Software)
Premium Member
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 23 Dec 2015, 09:55
chetan2u wrote:
appsy01 wrote:
Skywalker, I can understand the logic you used, but aren't we not allowed to equate sailboats and motorboats to each other?

If s was the initial no^ of sailboats and m was the initial number of motorboats, then, in the original equation, there is no relation given between then^

so, if we assume s#=5/4 s and m#=11/10 m, then #m#s#/m#= (5/4) s / (11/10) m => s# / m# =25s/22m => s/m = 22s#/25m# or 22/25 s#/m#[/m]
and in this case, the value of s/m will depend on s#/m# and hence statement I shouldn't be sufficient.

Is this assumption wrong?


hi,
you are correct prior to the coloured portion..
why are you taking ratio of s# and m#.... its not correct
what we require to do is equate both of them due to the statement
If the number of motorboats on Lake X had been 25% greater, the number of sailboats on Lake X would have been 110% of the number of motorboats on Lake X...
so here s#=m#..
or (5/4) s =(11/10) m .... get s and m on one side and you will have s/m and other side you will have the ratio


Ah! did not register the "would have been" clearly!

Thanks a lot for the clarification chetan
Manager
Manager
avatar
Status: tough ... ? Naaahhh !!!!
Joined: 08 Sep 2015
Posts: 64
Location: India
Concentration: Marketing, Strategy
WE: Marketing (Computer Hardware)
GMAT ToolKit User
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 23 Dec 2015, 10:35
(1) If the number of motorboats on Lake X had been 25% greater, the number of sailboats on Lake X would have been 110% of the number of motorboats on Lake X.
S=110/110(M+M/4)
S/M=8/11 ....Suff
(2) The positive difference between the number of motorboats on Lake X and the number of sailboats on Lake X was 30.
...M-S=30 ....Insuff

Ans: A
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6020
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 23 Dec 2015, 19:02
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

At a given time, what was the ratio of the number of sailboats to the number of motorboats on Lake X?

(1) If the number of motorboats on Lake X had been 25% greater, the number of sailboats on Lake X would have been 110% of the number of motorboats on Lake X.
(2) The positive difference between the number of motorboats on Lake X and the number of sailboats on Lake X was 30.

In the original condition and the question, consider the number of sailboats as ‘s’ and the number of motorboats as ‘m’. Then, you can come up with a question ‘s:m=?.’ However, when a ratio is asked in a question, it is likely that con is the ratio, which is an answer. So, in 1) s=1.1(1.25m), since s:m is unique, it is sufficient. In 2) |s-m|=30, since s:m is not unique, it is not sufficient. Therefore, the answer is A.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Director
Director
User avatar
G
Joined: 23 Jan 2013
Posts: 598
Schools: Cambridge'16
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 01 Mar 2016, 04:50
we need to find s/m

St.1 increasing m 1.25 times means that s/m ratio became 1.25 times less than original. So, original ratio was 1.25*1.1=1.375. SUFF

St.2 INSUFF.

A
Manager
Manager
User avatar
B
Joined: 25 Sep 2015
Posts: 132
Location: United States
GMAT 1: 700 Q48 V37
GPA: 3.26
Reviews Badge
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 01 Mar 2016, 17:46
1
chetan2u wrote:
appsy01 wrote:
Skywalker, I can understand the logic you used, but aren't we not allowed to equate sailboats and motorboats to each other?

If s was the initial no^ of sailboats and m was the initial number of motorboats, then, in the original equation, there is no relation given between then^

so, if we assume s#=5/4 s and m#=11/10 m, then #m#s#/m#= (5/4) s / (11/10) m => s# / m# =25s/22m => s/m = 22s#/25m# or 22/25 s#/m#[/m]
and in this case, the value of s/m will depend on s#/m# and hence statement I shouldn't be sufficient.

Is this assumption wrong?


hi,
you are correct prior to the coloured portion..
why are you taking ratio of s# and m#.... its not correct
what we require to do is equate both of them due to the statement
If the number of motorboats on Lake X had been 25% greater, the number of sailboats on Lake X would have been 110% of the number of motorboats on Lake X...
so here s#=m#..
or (5/4) s =(11/10) m .... get s and m on one side and you will have s/m and other side you will have the ratio


hi chetan2u

I don't understand your explanation.

I deduced x=1.1*1.25*y
(since it says if Y is 25%increased, X is 110% of y - Doesn't that mean 1.1*1.25*Y?)
Current Student
avatar
S
Joined: 20 Mar 2014
Posts: 2643
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44
GPA: 3.7
WE: Engineering (Aerospace and Defense)
GMAT ToolKit User Premium Member Reviews Badge
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 01 Mar 2016, 17:59
rachitshah wrote:
chetan2u wrote:
appsy01 wrote:
Skywalker, I can understand the logic you used, but aren't we not allowed to equate sailboats and motorboats to each other?

If s was the initial no^ of sailboats and m was the initial number of motorboats, then, in the original equation, there is no relation given between then^

so, if we assume s#=5/4 s and m#=11/10 m, then #m#s#/m#= (5/4) s / (11/10) m => s# / m# =25s/22m => s/m = 22s#/25m# or 22/25 s#/m#[/m]
and in this case, the value of s/m will depend on s#/m# and hence statement I shouldn't be sufficient.

Is this assumption wrong?


hi,
you are correct prior to the coloured portion..
why are you taking ratio of s# and m#.... its not correct
what we require to do is equate both of them due to the statement
If the number of motorboats on Lake X had been 25% greater, the number of sailboats on Lake X would have been 110% of the number of motorboats on Lake X...
so here s#=m#..
or (5/4) s =(11/10) m .... get s and m on one side and you will have s/m and other side you will have the ratio


hi chetan2u

I don't understand your explanation.

I deduced x=1.1*1.25*y
(since it says if Y is 25%increased, X is 110% of y - Doesn't that mean 1.1*1.25*Y?)


You are correct rachitshah. As per the given verbiage of statement 1, the equation if you have to set up will be s=1.1*1.25*m and not 1.25s = 1.1 m .

But the main point to note here is that this statement is sufficient to calculate the ratio of s/m at any given time.

Hope this helps.
Intern
Intern
avatar
B
Joined: 18 Sep 2016
Posts: 26
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 12 Aug 2017, 09:00
Bunuel wrote:
At a given time, what was the ratio of the number of sailboats to the number of motorboats on Lake X?

(1) If the number of motorboats on Lake X had been 25% greater, the number of sailboats on Lake X would have been 110% of the number of motorboats on Lake X.
(2) The positive difference between the number of motorboats on Lake X and the number of sailboats on Lake X was 30.


Can someone please give a detailed explanation to this problem. why 1.25m=1.1s?

The statement says "the number of sailboats on Lake X would have been 110% of the number of motorboats"

Doesnt it mean s=1.1m?
Current Student
avatar
S
Joined: 20 Mar 2014
Posts: 2643
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44
GPA: 3.7
WE: Engineering (Aerospace and Defense)
GMAT ToolKit User Premium Member Reviews Badge
Re: At a given time, what was the ratio of the number of sailboats to the  [#permalink]

Show Tags

New post 13 Aug 2017, 05:01
tejasridarsi wrote:
Bunuel wrote:
At a given time, what was the ratio of the number of sailboats to the number of motorboats on Lake X?

(1) If the number of motorboats on Lake X had been 25% greater, the number of sailboats on Lake X would have been 110% of the number of motorboats on Lake X.
(2) The positive difference between the number of motorboats on Lake X and the number of sailboats on Lake X was 30.


Can someone please give a detailed explanation to this problem. why 1.25m=1.1s?

The statement says "the number of sailboats on Lake X would have been 110% of the number of motorboats"

Doesnt it mean s=1.1m?


You are only quoting a part of the first statement and ignoring the red part above. This is where 1.25s will come from.
Re: At a given time, what was the ratio of the number of sailboats to the &nbs [#permalink] 13 Aug 2017, 05:01
Display posts from previous: Sort by

At a given time, what was the ratio of the number of sailboats to the

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  

Events & Promotions

PREV
NEXT


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.