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

Question

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

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

alpha_plus_gamma · Accepted Answer

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

Bunuel · Answer

The probability of survival  for each  of the first 3 months of life is  1-\frac{1}{10}=\frac{9}{10} , so of 200 newborn  200*\frac{9}{10}*\frac{9}{10}*\frac{9}{10} \approx 146  is expected to survive.

Answer: B.

ankush83gupta · Answer

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?

mgoblue123 · Answer

200 * .10 = 20 died

180 * .10= 18 died

162 * .10= 16.2 = 16 died

Total died = 54

200-54= 146 (B)

fluke · Answer

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"

Spidy001 · Answer

Good question.

Its important to see the given death probability is for one month, otherwise one can get this wrong.

mvictor · Answer

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.

Suruchii · Answer

In the question, shouldn't it be "the probability that  animals  die"? I got confused when I read the question. I read the question as the probability of one animal dying out of the 200 is 1/10.  Bunuel  Could you Please help understand

Rance14 · Answer

P(dead) = 1/10

P(not dead) = 1-1/10 = 9/10

P(not dead 1st month) = 200*9/10 = 180

P(not dead 2nd month) = 180*9/10 = 18*9

P(not dead 3rd month) = 18*9*9/10 = 18*81/10 = 1458/10 = 145.8 = 146 (approx)

option (B)

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

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