It is currently 18 Aug 2018, 22:07
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.

A machine is made up of two components, A and B. Each compon

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Moderator
Moderator
User avatar
Joined: 18 Apr 2015
Posts: 4148
Followers: 61

Kudos [?]: 766 [0], given: 3740

CAT Tests
A machine is made up of two components, A and B. Each compon [#permalink] New post 10 Aug 2018, 06:34
Expert's post
00:00

Question Stats:

33% (00:48) correct 66% (01:25) wrong based on 3 sessions
A machine is made up of two components, A and B. Each component either works or fails. The failure or non-failure of one component is independent of the failure or non-failure of the other component. The machine works if at least one of the components works.

If the probability that each component works is \(\frac{2}{3}\), what is the probability that the machine works?

A. \(\frac{1}{9}\)

B. \(\frac{4}{9}\)

C. \(\frac{1}{2}\)

D. \(\frac{2}{3}\)

E. \(\frac{8}{9}\)

Kudos for R.A.E.
[Reveal] Spoiler: OA

_________________

Get the 2 FREE GREPrepclub Tests

1 KUDOS received
Intern
Intern
Joined: 10 Aug 2018
Posts: 33
Followers: 0

Kudos [?]: 10 [1] , given: 0

CAT Tests
Re: A machine is made up of two components, A and B. Each compon [#permalink] New post 10 Aug 2018, 09:50
1
This post received
KUDOS
I don't know if this is poor form as I just joined, so moderators please stop me if I'm doing things I shouldn't.

Explanation below:

We want to know if the machine works, or in other words if the machine doesn't fail. The only case where the machine fails is when both the components fail.

We know that each component fail independently of the other components, and as the probability that each component works is 2/3, the probability that each component fails is 1-2/3, or 1/3.

Then we can figure out the probability that the machine fails. It is the probability that the first component fails times the probability that the second component fails.

1/3*1/3 = 1/9

Thus the probability that the machine fails is 1/9. The probability that the machine works is then the complement of this probability (success = 1-failure), or 1-1/9 = 8/9.

So we pick E.
Moderator
Moderator
User avatar
Joined: 18 Apr 2015
Posts: 4148
Followers: 61

Kudos [?]: 766 [0], given: 3740

CAT Tests
Re: A machine is made up of two components, A and B. Each compon [#permalink] New post 10 Aug 2018, 14:42
Expert's post
No need to encapsulate the answer in the tag [spoiler]

Just leave your reply.

Regards
_________________

Get the 2 FREE GREPrepclub Tests

Re: A machine is made up of two components, A and B. Each compon   [#permalink] 10 Aug 2018, 14:42
Display posts from previous: Sort by

A machine is made up of two components, A and B. Each compon

  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®.