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.
Sep 1507:00 PM EDT
-09:00 PM EST
Elite scores are possible when you enroll in a powerful GMAT course, taught live online + 6 months access to TTP OnDemand video courses included! Class starts Tues/Thurs Sept. 15, 2026 - Nov. 15, 2027, 7:00pm-9:00pm EST
Sep 2107:00 PM EDT
-10:00 PM EDT
Boost your GMAT score in less than one month in a live online class + 6 months access to TTP OnDemand video courses included! Class starts Mon, Tues, Wed, Thur, Fri Sept. 21, 2026 - Oct. 9, 2027, 7:00pm-10:00pm EST
01 Apr 2013, 01:18
Kudos
Bookmarks
One fourth of a group of infected people will die everyday due to a virus. What fraction of this group would be expected to be killed after 4 days?
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!
01 Apr 2013, 09:56
Kudos
Bookmarks
score780
suppose the number of people in the start is T
people dying on 1st day = (1/4)*T= T/4
people left = 3T/4
on, 2nd day the number of people dying = (1/4)(3/4)T = (3/16)T
no of people left = (9/16)T
on, 3rd day the number of people dying = (1/4)(9/16)T = (9/64)T
no. of people left = (27/64) T
on, 4th day the number of people dying = (1/4)(27/64)T = (27/256)T
no. of people left = (81/256) T
Probability of number of people killed in 4days = total killed in 4days/ total number of people in the starting = ((T/4) + (3T/16) + (9T/64) + (27T/64) )/ T
= (1/4) + (3/16) + (9/64) + (27/256) = (64 + 16*3 + 4*9 + 27)/256 = (64+48+36+27) /256 = 175/256
hope it helps!
01 Apr 2013, 21:26
Kudos
Bookmarks
Find the number of people who are alive at the end of day 4 and then subtract that from the beginning amount.
So at end of day 0, there are x people.
Therefore, there are 3x/4 people at the end of day 1.
And (3x/4) * (3/4) at the end of day 2. >>> 9x/16
And (9x/16) * (3/4) at the end of day 3. >>> 27x/64
And (27x/64) * (3/4) at the end of day 4. >>> 81x/256
So x - (81x/256) is the number of people who died by the end of day 4.
Which is (256x/256) - (81x/256) = (175x/256).
And so, the answer is 175/256, which can be broken down into prime factors: (5^2)(7) / 2^8. So, the answer can't be simplified further.
So at end of day 0, there are x people.
Therefore, there are 3x/4 people at the end of day 1.
And (3x/4) * (3/4) at the end of day 2. >>> 9x/16
And (9x/16) * (3/4) at the end of day 3. >>> 27x/64
And (27x/64) * (3/4) at the end of day 4. >>> 81x/256
So x - (81x/256) is the number of people who died by the end of day 4.
Which is (256x/256) - (81x/256) = (175x/256).
And so, the answer is 175/256, which can be broken down into prime factors: (5^2)(7) / 2^8. So, the answer can't be simplified further.
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 above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
