Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 26 May 2017, 10:02

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# In a certain animal population, for each of the first 3 mont

Author Message
TAGS:

### Hide Tags

Intern
Joined: 20 Jul 2008
Posts: 6
Followers: 0

Kudos [?]: 5 [1] , given: 0

In a certain animal population, for each of the first 3 mont [#permalink]

### Show Tags

20 Aug 2008, 01:52
1
KUDOS
4
This post was
BOOKMARKED
00:00

Difficulty:

35% (medium)

Question Stats:

68% (02:16) correct 32% (01:19) wrong based on 367 sessions

### HideShow timer Statistics

In a certain animal population, for each of the first 3 months of life, the probability that an animal will die during that month is 1/10. For a group of 200 newborn members of the population, approximately how many would be expected to survive the first 3 months of life?

A. 140
B. 146
C. 152
D. 162
E. 170
[Reveal] Spoiler: OA

Last edited by Bunuel on 17 Aug 2014, 09:25, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
Intern
Joined: 13 Aug 2008
Posts: 17
Followers: 0

Kudos [?]: 3 [2] , given: 0

Re: In a certain animal population, for each of the first 3 mont [#permalink]

### Show Tags

20 Aug 2008, 02:50
2
KUDOS
1
This post was
BOOKMARKED
My take,
P(animal dying during first 3 months) = P(dying in M1) + P(dying in M2) + P(dying in M3)
= (1/10) + (9/10)*(1/10) + (9/10)*(9/10)*(1/10)
= 271/1000

P(animal surviving the first 3 months) = 729/1000

No Of animals surviving (approx) = (729/1000) * 200 = 146

What is the OA?
Director
Joined: 14 Aug 2007
Posts: 729
Followers: 10

Kudos [?]: 197 [2] , given: 0

Re: In a certain animal population, for each of the first 3 mont [#permalink]

### Show Tags

20 Aug 2008, 04:52
2
KUDOS
1
This post was
BOOKMARKED
Ginc wrote:
In a certain animal population for each of the first 3 months of life, the probability that an animal will die during that month is 1/10. For a group of 200 newborn members of the population, aprroximately how many would be expected to survive the first 3 month of life?
a)140
b)146
c)152
d)162
e)170

How would you solve this? Thanks

Number of newborns that can die in first month = 1/10 * 200 = 20

Survived = 180

Number of newborns that can die in second month = 1/10 * 180 = 18

Survived = 162

Number of newborns that can die in third month = 1/10 * 162 = 16

Survived = 146
Manager
Joined: 27 Mar 2008
Posts: 81
Followers: 1

Kudos [?]: 108 [0], given: 0

Re: In a certain animal population, for each of the first 3 mont [#permalink]

### Show Tags

20 Aug 2008, 13:50
200 * .10 = 20 died

180 * .10= 18 died

162 * .10= 16.2 = 16 died

Total died = 54

200-54= 146 (B)
Math Forum Moderator
Joined: 20 Dec 2010
Posts: 2013
Followers: 163

Kudos [?]: 1825 [0], given: 376

### Show Tags

12 Mar 2011, 12:39
200/10=20 will die in the first month.
Left 180
180/10=18 will die in the 2nd
Left 162
162/10=16.2=16 will die in the 3rd

Total dead = 20+18+16 = 54
Alive = 200-54= 146

Ans: "B"
_________________
Math Expert
Joined: 02 Sep 2009
Posts: 38908
Followers: 7739

Kudos [?]: 106215 [1] , given: 11613

### Show Tags

12 Mar 2011, 12:41
1
KUDOS
Expert's post
1
This post was
BOOKMARKED
In a certain animal population, for each of the first 3 months of life, the probability that an animal will die during that month is 1/10. For a group of 200 newborn members of the population, approximately how many would be expected to survive the first 3 months of life?
A/ 140
B/ 146
C/ 152
D/ 162
E/ 170

The probability of survival for each of the first 3 months of life is 1-1/10=9/10, so of 200 newborn 200*9/10*9/10*9/10=~146 is expected to survive.

_________________
Director
Joined: 01 Feb 2011
Posts: 755
Followers: 14

Kudos [?]: 125 [0], given: 42

### Show Tags

12 Mar 2011, 12:48
Good question.

Its important to see the given death probability is for one month, otherwise one can get this wrong.
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15463
Followers: 649

Kudos [?]: 209 [0], given: 0

Re: In a certain animal population, for each of the first 3 mont [#permalink]

### Show Tags

17 Aug 2014, 07:26
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 15463
Followers: 649

Kudos [?]: 209 [0], given: 0

Re: In a certain animal population, for each of the first 3 mont [#permalink]

### Show Tags

31 Oct 2015, 10:58
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Intern
Joined: 27 Aug 2014
Posts: 1
Schools: ISB '16, NUS '16, NTU '17
GMAT 1: 580 Q40 V25
GMAT 2: 600 Q42 V31
Followers: 0

Kudos [?]: 0 [0], given: 0

Re: In a certain animal population, for each of the first 3 mont [#permalink]

### Show Tags

01 Nov 2015, 23:00
Bunuel wrote:
In a certain animal population, for each of the first 3 months of life, the probability that an animal will die during that month is 1/10. For a group of 200 newborn members of the population, approximately how many would be expected to survive the first 3 months of life?
A/ 140
B/ 146
C/ 152
D/ 162
E/ 170

The probability of survival for each of the first 3 months of life is 1-1/10=9/10, so of 200 newborn 200*9/10*9/10*9/10=~146 is expected to survive.

Hi Bunuel,

If probability of survival can be calculated with 3 times 9/10 , the same can apply to probability of death for 3 months. But the answers would be different.

200*1/10*1/10*1/10 = 0.2.

Can you explain why this approach does not work ?
Thanks.
CEO
Joined: 17 Jul 2014
Posts: 2502
Location: United States (IL)
Concentration: Finance, Economics
Schools: Stanford '19 (D)
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
Followers: 26

Kudos [?]: 342 [0], given: 168

Re: In a certain animal population, for each of the first 3 mont [#permalink]

### Show Tags

16 Sep 2016, 07:37
Ginc wrote:
In a certain animal population, for each of the first 3 months of life, the probability that an animal will die during that month is 1/10. For a group of 200 newborn members of the population, approximately how many would be expected to survive the first 3 months of life?

A. 140
B. 146
C. 152
D. 162
E. 170

the critical mistake here is to think that 1/10 per month, 3 months is 3/10 this will yield an answer choice that is a trap - A.
1/10 * 200 = 180 - how many will survive 1st month - we can eliminate A and E.
180 * 1/10 = 162 - how many will survive 2nd month - we can eliminate A, D, and E.
so it's between B and C.
162 = 100%, 16.2 = 10%. 162-16 = 146 aprox. so B.
Re: In a certain animal population, for each of the first 3 mont   [#permalink] 16 Sep 2016, 07:37
Similar topics Replies Last post
Similar
Topics:
16 At the start of an experiment, a certain population consisted of 3 10 27 Mar 2017, 11:54
8 In a certain sequence of 8 numbers, each number after the first is 1 12 15 Feb 2017, 09:15
1 In a certain series, each term (except for the first term) is one grea 1 14 Jun 2015, 11:58
4 In a certain sequence, the first term is 2, and each successive term 5 12 Jun 2015, 10:28
4 In a certain population, there are 3 times as many people ag 7 21 Nov 2016, 23:01
Display posts from previous: Sort by