It is currently 20 Jul 2019, 13:52
My Tests

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.

From a box of 10 lightbulbs, you are to remove 4. How many d

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Founder
Founder
User avatar
Joined: 18 Apr 2015
Posts: 7395
Followers: 124

Kudos [?]: 1449 [0], given: 6602

CAT Tests
From a box of 10 lightbulbs, you are to remove 4. How many d [#permalink] New post 30 May 2019, 11:24
Expert's post
From a box of 10 lightbulbs, you are to remove 4. How many different sets of 4 lightbulbs could you remove?

[Reveal] Spoiler: OA
210


Math Review
Question: 9
Page: 297
Difficulty: medium

_________________

Get the 2 FREE GREPrepclub Tests

1 KUDOS received
GRE Instructor
User avatar
Joined: 10 Apr 2015
Posts: 2170
Followers: 64

Kudos [?]: 1982 [1] , given: 20

CAT Tests
Re: From a box of 10 lightbulbs, you are to remove 4. How many d [#permalink] New post 31 May 2019, 05:07
1
This post received
KUDOS
Expert's post
Carcass wrote:
From a box of 10 lightbulbs, you are to remove 4. How many different sets of 4 lightbulbs could you remove?

[Reveal] Spoiler: OA
210


Math Review
Question: 9
Page: 297
Difficulty: medium


In this case, the order in which we select the 4 bulbs does not matter.
For example, selecting bulb A, then bulb D, then bulb E, and then bulb H, is the SAME as selecting bulb H, then bulb D, then bulb A, and then bulb E
So, we can use COMBINATIONS.

We can select 4 bulbs from 10 bulbs in 10C4 ways

10C4 = (10)(9)(8)(7)/(4)(3)(2)(1) = 210

Answer: 210

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com
Image
Sign up for my free GRE Question of the Day emails

Re: From a box of 10 lightbulbs, you are to remove 4. How many d   [#permalink] 31 May 2019, 05:07
Display posts from previous: Sort by

From a box of 10 lightbulbs, you are to remove 4. How many d

  Question banks Downloads My Bookmarks Reviews Important topics  


GRE Prep Club Forum Home| About| Terms and Conditions and Privacy Policy| GRE Prep Club Rules| Contact

Powered by phpBB © phpBB Group

Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.