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.
Jun 0308:30 AM PDT
-09:30 AM PDT
In Episode 7 of our GMAT Ninja CR series, we are rounding up the oddballs, the misfits, and the format-benders: EXCEPT, Fill-In-The-Blanks, and other unusual Critical Reasoning question types. When you see a question that ends with a literal blank line
May 2910:00 AM IST
-11:00 PM IST
Start your journey with a fully customized action plan and work with a dedicated mentor to achieve a 735+ score.- Jun 02
10:00 AM PDT
-11:00 AM PDT
Probability is one of the most important GMAT Quant topics because it often combines logic, counting, set theory, and permutations & combinations. Many students try to solve probability questions by listing every possible case, but GMAT probability... - Jun 04
08:30 AM PDT
-09:30 AM PDT
For most test takers, Data Insights is the most challenging section on the GMAT, with test takers scoring several points lower on average on DI than on Quant or Verbal and completing the section with less time to spare. - Jun 10
06:00 AM PDT
-06:15 PM PDT
Register for the GMAT Club Virtual MBA Spotlight Fair – the world’s premier event for serious MBA candidates. This is your chance to hear directly from Admissions Directors at nearly every Top 30 MBA program..
12 Aug 2017, 15:51
Kudos
Bookmarks
Jill has applied for a job with each of two different companies A & B. Some probabilities are given in the Venn diagram (attached file), solve for P (A & B) and P (None).
Could someone please help me figure out the discrepancy between Venn Diagram solution vs probability solution while trying to solve for P (A & B) and P (None)? I'm getting different values for both if I try using those 2 different methods as shown by "??" in the uploaded file.
I was running into a similar issue while trying to solve OG17 DS283, so I made this simplified Q for understanding the basics.
Thanks!
Could someone please help me figure out the discrepancy between Venn Diagram solution vs probability solution while trying to solve for P (A & B) and P (None)? I'm getting different values for both if I try using those 2 different methods as shown by "??" in the uploaded file.
I was running into a similar issue while trying to solve OG17 DS283, so I made this simplified Q for understanding the basics.
Thanks!
Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
Attachments
ProbabilityUsingVenn.jpg [ 1.06 MiB | Viewed 5845 times ]
12 Aug 2017, 16:05
Kudos
Bookmarks
The rule P(A and B) = P(A)*P(B) is only true if A and B are "independent". That is, it's only true if the outcome of A has no influence on whether B happens. That's sometimes true in real life -- if you roll a die and flip a coin, say, one event has no influence on the other. But it's sometimes not true -- the probability it rains in one city is probably very closely related to the probability it rains in a neighbouring city. In that case, you couldn't use the multiplication rule.
In your Venn diagram, your two events are not independent. If they were independent, then any time the applicant got job A, they'd still have a 50% chance of getting job B. But they don't - when they get job A, they only get job B 3/7 of the time (0.7 of the time they get A, and 0.3 of the time they get both). Since your events are not independent, you can't use the familiar multiplication laws in that situation, and you'd normally need to solve using another method, like the Venn diagram you've drawn.
Fortunately on the GMAT, in almost all questions, events are independent, so you will almost always be able to use the simple multiplication rules when you want the probability two events happen.
In your Venn diagram, your two events are not independent. If they were independent, then any time the applicant got job A, they'd still have a 50% chance of getting job B. But they don't - when they get job A, they only get job B 3/7 of the time (0.7 of the time they get A, and 0.3 of the time they get both). Since your events are not independent, you can't use the familiar multiplication laws in that situation, and you'd normally need to solve using another method, like the Venn diagram you've drawn.
Fortunately on the GMAT, in almost all questions, events are independent, so you will almost always be able to use the simple multiplication rules when you want the probability two events happen.
13 Aug 2017, 08:44
Kudos
Bookmarks
IanStewart
Thanks IanStewart. In that case, would the independent events have a Venn diagram with two disjoint circles or overlapping lapping with extremely small overlap? My understanding is that they will have an extremely small overlap as shown in my uploaded file. Since the overlap for such events (i.e. my example on the right half of the page) is so small [Comparing P(A) = P(B) = 0.1 to P (A&B) = 0.1*0.1 = 0.01), they are called independent events even though they have a minor overlap.
Are events considered independent only when P(A&B) = P(A)P(B)?
Please correct me if my understanding is not fully correct. Thanks!
Attachments
DependentVsIndependentEvents.png [ 2.51 MiB | Viewed 5719 times ]
