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

 It is currently 16 Jan 2019, 08:25

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

Events & Promotions

Events & Promotions in January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
• The winning strategy for a high GRE score

January 17, 2019

January 17, 2019

08:00 AM PST

09:00 AM PST

Learn the winning strategy for a high GRE score — what do people who reach a high score do differently? We're going to share insights, tips and strategies from data we've collected from over 50,000 students who used examPAL.
• Free GMAT Strategy Webinar

January 19, 2019

January 19, 2019

07:00 AM PST

09:00 AM PST

Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.

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

Author Message
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 52161
At a hobby store, the ratio of telescopes to microscopes is currently  [#permalink]

Show Tags

10 Apr 2018, 20:47
00:00

Difficulty:

15% (low)

Question Stats:

87% (01:12) correct 13% (01:28) wrong based on 64 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

_________________
examPAL Representative
Joined: 07 Dec 2017
Posts: 867
Re: At a hobby store, the ratio of telescopes to microscopes is currently  [#permalink]

Show Tags

10 Apr 2018, 22:01
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!

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

Show Tags

10 Apr 2018, 23:45
1
3x/2x-10=2/1, we get x=20
Thus, the no. of telescopes=60
Manager
Joined: 22 Jun 2017
Posts: 71
Location: Brazil
GMAT 1: 600 Q48 V25
GPA: 3.5
WE: Engineering (Energy and Utilities)
At a hobby store, the ratio of telescopes to microscopes is currently  [#permalink]

Show Tags

12 Apr 2018, 09:01
$$\frac{t}{m}$$ = $$\frac{3}{2}$$ > 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)
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 4518
Location: United States (CA)
Re: At a hobby store, the ratio of telescopes to microscopes is currently  [#permalink]

Show Tags

12 Apr 2018, 15:23
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.

_________________

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, 15:23
Display posts from previous: Sort by