Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
Apr 2912:30 AM EDT
-01:30 AM EDT
Learn how Kamakshi achieved a GMAT 675 with an impressive 96th %ile in Data Insights. Discover the unique methods and exam strategies that helped her excel in DI along with other sections for a balanced and high score.
Apr 3001:30 AM EDT
-02:30 AM EDT
At one point, she believed GMAT wasn’t for her. After scoring 595, self-doubt crept in and she questioned her potential. But instead of quitting, she made the right strategic changes. The result? A remarkable comeback to 695. Check out how Saakshi did it.
May 0111:00 AM PDT
-12:00 PM PDT
Free- full-length test + 15 concept videos + 150+ short videos + study plan!
May 0306:30 AM PDT
-08:30 AM PDT
Verbal trouble on GMAT? Fix it NOW! Join Sunita Singhvi for a focused webinar on actionable strategies to boost your Verbal score and take your performance to the next level.
28 Jan 2019, 02:19
Kudos
Bookmarks
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
67% (01:32) correct
33%
(01:23)
wrong
based on 218
sessions
History
Date
Time
Result
Not Attempted Yet
Of the 20 lightbulbs in a box, 2 are defective. An inspector will select 2 lightbulbs simultaneously and at random from the box. What is the probability that neither of the lightbulbs selected will be defective?
A. 37/190
B. 17/19
C. 9/10
D. 153/190
E. 189/190
A. 37/190
B. 17/19
C. 9/10
D. 153/190
E. 189/190
Archit3110
Major Poster
Updated on: 29 Jan 2019, 01:45
Originally posted by Archit3110 on 28 Jan 2019, 04:24.
Last edited by Archit3110 on 29 Jan 2019, 01:45, edited 1 time in total.
Last edited by Archit3110 on 29 Jan 2019, 01:45, edited 1 time in total.
Kudos
Bookmarks
Bunuel
P of picking bulbs not defective ;
18/20 * 17/19 = 153/190
IMO D
28 Jan 2019, 19:40
Kudos
Bookmarks
Don't be confused by the wording. This is your basic –"red marbles in a jar" - probability question. Simultaneously is treated the same as take one, don't replace, then take another.
The probability space (the denominator) is 20·19. There are initially 20 lightbulbs to choose from. When one is taken, there are only 19.
The numerator is 18·17. Neither of the lightbulbs selected will be defective so we can pick any lightbulb bar the defective ones. 20-2=18. The defective ones stay. Now there are 19 lightbulbs and still two defective ones 19-2=17.
\(\frac{18}{20}·\frac{17}{19}=\frac{9}{10}·\frac{17}{19}=\frac{153}{190}\)=D
The probability space (the denominator) is 20·19. There are initially 20 lightbulbs to choose from. When one is taken, there are only 19.
The numerator is 18·17. Neither of the lightbulbs selected will be defective so we can pick any lightbulb bar the defective ones. 20-2=18. The defective ones stay. Now there are 19 lightbulbs and still two defective ones 19-2=17.
\(\frac{18}{20}·\frac{17}{19}=\frac{9}{10}·\frac{17}{19}=\frac{153}{190}\)=D
