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In a certain animal population, for each of the first 3 mont
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Updated on: 17 Aug 2014, 08:25
Question Stats:
69% (01:47) correct 31% (01:56) wrong based on 442 sessions
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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
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Originally posted by Ginc on 20 Aug 2008, 00:52.
Last edited by Bunuel on 17 Aug 2014, 08:25, edited 1 time in total.
Renamed the topic, edited the question and added the OA.




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Re: In a certain animal population, for each of the first 3 mont
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20 Aug 2008, 03:52
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




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Re: In a certain animal population, for each of the first 3 mont
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20 Aug 2008, 01:50
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?



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Re: In a certain animal population, for each of the first 3 mont
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20 Aug 2008, 12:50
200 * .10 = 20 died
180 * .10= 18 died
162 * .10= 16.2 = 16 died
Total died = 54
20054= 146 (B)



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Re: Animal population
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12 Mar 2011, 11:39
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 = 20054= 146 Ans: "B"
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Re: Animal population
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12 Mar 2011, 11:41



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Re: Animal population
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12 Mar 2011, 11:48
Good question.
Its important to see the given death probability is for one month, otherwise one can get this wrong.



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Re: In a certain animal population, for each of the first 3 mont
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01 Nov 2015, 22:00
Bunuel wrote: Madelaine88 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 11/10=9/10, so of 200 newborn 200*9/10*9/10*9/10=~146 is expected to survive. Answer: B. 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.



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Re: In a certain animal population, for each of the first 3 mont
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16 Sep 2016, 06:37
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%. 16216 = 146 aprox. so B.



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Re: In a certain animal population, for each of the first 3 mont
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21 Jul 2018, 07:38
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