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 0210:00 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...
May 2110:00 AM EDT
-11:59 PM EDT
Make the most of your break with the most realistic GMAT™ prep. Take up to $700 off select products.
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 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..
18 Jul 2009, 10:00
Kudos
Bookmarks
N
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
(N/A)
Question Stats:
0% (00:00) correct
0%
(00:00)
wrong
based on 0
sessions
History
Date
Time
Result
Not Attempted Yet
Help Needed Prep Question
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 Problem Solving (PS) 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!
18 Jul 2009, 13:01
Kudos
Bookmarks
I got this questions while doing the simulation as well.
This is what I did.
The first part of the equation, \((-1)^k+1\), will only determine whether the number is positive or negative.
For k = 1, this part will be 1
For k = 2, this part will be -1
For k = 3, this part will be 1, again. Thus, when k is even the term will be multiple by -1, and it will be negative. However, when k is odd the term will be positive.
The second part of the equation just tell us that is a fraction of power of 2.
Thus the numbers are:
\(1/2, -1/4, 1/8, -1/16, 1/32, -1/64, 1/128, -1/256, 1/512, -1/1024\)
Now try to sum the first positives to have a impression of the sum of the positives, and do the same with the negatives.
If you transform them to decimal, you will notice that the first positives, are, 0.5, 0.125, 0.03, now hold on. The sum here is 0.655. The way the numbers are going down to fast, you can see that this sum will not pass 0.7, or if it pass, it will be very close to 0.7. Save this number.
Now, if you sum the negatives, in decimal, you will see -0.25, -0.06, ok that is enough. You do not need even to continue. As you can see, again the numbers are going down ("modularity talking") so fast that you can see the the sum will be around -0.3.
Thus \(0.7 - 0.3 =~ 0.4\), your answer approximately.
D between 0.25 and 0.5
This is what I did.
The first part of the equation, \((-1)^k+1\), will only determine whether the number is positive or negative.
For k = 1, this part will be 1
For k = 2, this part will be -1
For k = 3, this part will be 1, again. Thus, when k is even the term will be multiple by -1, and it will be negative. However, when k is odd the term will be positive.
The second part of the equation just tell us that is a fraction of power of 2.
Thus the numbers are:
\(1/2, -1/4, 1/8, -1/16, 1/32, -1/64, 1/128, -1/256, 1/512, -1/1024\)
Now try to sum the first positives to have a impression of the sum of the positives, and do the same with the negatives.
If you transform them to decimal, you will notice that the first positives, are, 0.5, 0.125, 0.03, now hold on. The sum here is 0.655. The way the numbers are going down to fast, you can see that this sum will not pass 0.7, or if it pass, it will be very close to 0.7. Save this number.
Now, if you sum the negatives, in decimal, you will see -0.25, -0.06, ok that is enough. You do not need even to continue. As you can see, again the numbers are going down ("modularity talking") so fast that you can see the the sum will be around -0.3.
Thus \(0.7 - 0.3 =~ 0.4\), your answer approximately.
D between 0.25 and 0.5
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 Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
Moderator:
