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

It is currently 25 Jun 2018, 08:26

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If a jury of 12 people is to be selected randomly from a

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

Hide Tags

Senior Manager
Senior Manager
User avatar
S
Joined: 08 Dec 2015
Posts: 304
GMAT 1: 600 Q44 V27
Reviews Badge
If a jury of 12 people is to be selected randomly from a [#permalink]

Show Tags

New post 08 Jun 2016, 09:41
A guessing strategy from Magoosh:

When you see that the problem can be solved using the 1-(P of opposite), in this case 1-(P of 5 women being selected), find two choices among the answers that added together yield 1. (no calculations what so ever, just the addition of any two answers must have 1 as result)

In this case its A and D. No other answers combo gives you 1 as result of addition.

When you subtract 24/91 from 1 you get 67/97, so the final answer. And we are looking for these "pairs" in the answer choices.

The P(5 women being selected) is a trap answer for those who forget to subtract that from 1. So the existence of these trap-answers that are supposed to confuse you allows you to use this strategy on a well-designed, typical GMAT question.

Then you have a 50% guess or:

see that you have a +- 33% chance (A) and a +-66% chance (D) choices. You can reason that the nº of men is quite large so its likely that the jury will be comprised mostly of men. so D looks like a good guess.

Thanks to Magoosh ;)
Magoosh Discount CodesOptimus Prep Discount CodesManhattan GMAT Discount Codes
Director
Director
User avatar
G
Joined: 26 Oct 2016
Posts: 666
Location: United States
Concentration: Marketing, International Business
Schools: HBS '19
GMAT 1: 770 Q51 V44
GPA: 4
WE: Education (Education)
Re: If a jury of 12 people is to be selected randomly from a [#permalink]

Show Tags

New post 07 Jan 2017, 09:30
Approach 1:-



Another way to solve this is "1-x" prob shortcut.
We need to know what is the probability of 7 men in jury, since it is the only way there are fewer than 8 men in jury ( maximum number of women is 5 ==> so 12-5=7 must be men). Then you have to 1-prob.of.7men.

1) All possible ways to assemble jury are : 15!/12!3!=455.
2) 7 of 10 men : 10!/7!3!=120
3) and the only way to include all women in jury is 5!/5!=1.

All possible ways to assemble 7men-5women jury will be 120*1=120.
Then, 120/455=24/91 - is the probability of 7 men and 5 woman in jury.
Hence, the probability that there will be more than 7 men in the jury is (1 - 24/91)=67/


Approach 2:-


there are total 10 men and 5 women
in 12 jury members, could be:

M W T
10+2=12
9+3=12
8+4=12
7+5=12
M-men , W-women T - total

So out of 4 possible outcomes 3 are favourbale, 1 is unfavorable, it is 3/4=0.75

67/91~73%., which is the closest to 3/4.
_________________

Thanks & Regards,
Anaira Mitch

Expert Post
EMPOWERgmat Instructor
User avatar
D
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 11834
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Re: If a jury of 12 people is to be selected randomly from a [#permalink]

Show Tags

New post 05 Mar 2018, 12:31
Hi All,

Yes, you CAN answer the question by solving the individual calculations that you listed. Here's how….

Since we're selecting 12 people from a group of 15, and the order doesn't matter, we can use the combination formula:

N!/[K!(N-K)!]

15c12 = 15!/[12!(3!)] = 455 possible groups of 12

Now we calculate each of the possible options that fits what we're looking for:

8 men (from 10) and 4 women (from 5) = (10c8)(5c4) = (45)(5) = 225
9 men (from 10) and 3 women (from 5) = (10c9)(5c3) = (10)(10) = 100
10 men (from 10) and 2 women (from 5) = (10c10)(5c2) = (1)(10) = 10

Total options with at least 8 men = 335

Probability = 335/455 = 67/91

Final Answer:

GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free
  Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************

Re: If a jury of 12 people is to be selected randomly from a   [#permalink] 05 Mar 2018, 12:31

Go to page   Previous    1   2   [ 23 posts ] 

Display posts from previous: Sort by

If a jury of 12 people is to be selected randomly from a

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


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®.