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

It is currently 23 Jul 2018, 06:46

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 hobby store, the ratio of telescopes to microscopes is currently

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

Hide Tags

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47219
At a hobby store, the ratio of telescopes to microscopes is currently  [#permalink]

Show Tags

New post 10 Apr 2018, 21:47
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

81% (01:04) correct 19% (01:26) wrong based on 58 sessions

HideShow timer Statistics

At a hobby store, the ratio of telescopes to microscopes is currently 3:2. If 10 microscopes were to be sold, that ratio would then be 2:1. How many telescopes does the store have?

A. 15
B. 30
C. 45
D. 60
E. 75

_________________

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

Expert Post
examPAL Representative
User avatar
S
Joined: 07 Dec 2017
Posts: 507
Re: At a hobby store, the ratio of telescopes to microscopes is currently  [#permalink]

Show Tags

New post 10 Apr 2018, 23:01
Bunuel wrote:
At a hobby store, the ratio of telescopes to microscopes is currently 3:2. If 10 microscopes were to be sold, that ratio would then be 2:1. How many telescopes does the store have?

A. 15
B. 30
C. 45
D. 60
E. 75


As word problems involving a change in ratios can be confusing, we'll instead use the answers.
This is an Alternative approach.

Say the median, (C), were correct, that is there are 45 telescopes in the store.
Then there are 45/3*2 = 30 microscopes. Subtracting 10 gives a ratio of 45:20 which is not 2:1. No!
We need to make the ratio smaller so we'll choose a larger answer.
Say (D). Then there are 60/3*2 = 40 microscopes and subtracting 10 gives 60:30=2:1. Yes!

(D) is our answer.
_________________

David
Senior tutor at examPAL
Signup for a free GMAT course
Image
We won some awards:
Image
Save up to $250 on examPAL packages (special for GMAT Club members)

1 KUDOS received
Intern
Intern
avatar
B
Joined: 31 Jul 2017
Posts: 11
Re: At a hobby store, the ratio of telescopes to microscopes is currently  [#permalink]

Show Tags

New post 11 Apr 2018, 00:45
1
i got Answer D.
3x/2x-10=2/1, we get x=20
Thus, the no. of telescopes=60
Manager
Manager
User avatar
B
Joined: 22 Jun 2017
Posts: 60
Location: Brazil
WE: Engineering (Energy and Utilities)
GMAT ToolKit User Premium Member CAT Tests
At a hobby store, the ratio of telescopes to microscopes is currently  [#permalink]

Show Tags

New post 12 Apr 2018, 10:01
\(\frac{t}{m}\) = \(\frac{3}{2}\) > 3m = 2t > m = \(\frac{2t}{3}\)

\(\frac{t}{(m-10)}\) = \(\frac{2}{1}\)

\(\frac{t}{((2t/3)-10)}\) = 2 > t = \(\frac{4t}{3}\) - 20 > 3t = 4t - 60 > t = 60 (Option D)
Expert Post
Target Test Prep Representative
User avatar
G
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 2992
Location: United States (CA)
Re: At a hobby store, the ratio of telescopes to microscopes is currently  [#permalink]

Show Tags

New post 12 Apr 2018, 16:23
Bunuel wrote:
At a hobby store, the ratio of telescopes to microscopes is currently 3:2. If 10 microscopes were to be sold, that ratio would then be 2:1. How many telescopes does the store have?

A. 15
B. 30
C. 45
D. 60
E. 75



We are given that the ratio of telescopes to microscopes = 3x : 2x, so we can create the equation:

3x/(2x - 10) = 2/1

2(2x - 10) = 3x

4x - 20 = 3x

x = 20

So there are currently 3 x 20 = 60 telescopes.

Answer: D
_________________

Scott Woodbury-Stewart
Founder and CEO

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Re: At a hobby store, the ratio of telescopes to microscopes is currently &nbs [#permalink] 12 Apr 2018, 16:23
Display posts from previous: Sort by

At a hobby store, the ratio of telescopes to microscopes is currently

  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®.