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Twenty-percent of the residents of Boston were born outside of the United States. A random sample of 400 residents is to be selected. Without using the Z table, compute the approximate probability that at least 22% of those in the sample were born outside of the United States.

 Mar 27, 2016

Best Answer 

 #3
avatar+33661 
+20

My reasoning is as follows:

 

prob

However, since it's a question of probabilities, I don't guarantee that my reasoning is correct!!

 Mar 29, 2016
 #1
avatar+118677 
0

Solveit asked me to look at this question.

I saw it when it was first posted and I wasn't really sure.   I am still not sure.

I'd guess the answer is 50%    That seems logical to me .......

 

Would anyone like to comment?  

 Mar 29, 2016
 #2
avatar+2498 
0

why 50% ? :D

Solveit  Mar 29, 2016
 #3
avatar+33661 
+20
Best Answer

My reasoning is as follows:

 

prob

However, since it's a question of probabilities, I don't guarantee that my reasoning is correct!!

Alan Mar 29, 2016
 #4
avatar+118677 
0

Well Alan, at least you have some reasoning.  I think that beats my guess     LOL.  

Melody  Mar 29, 2016
 #5
avatar+2498 
0

But what if i wanna to find probability that there is only 88 residents outside of US:

nCr(400, 88)*0.8^312*0.2^88 = 0.0294786177861719029113601772508066971031878720367673319179859403

nCr(400, 312)*0.8^312*0.2^88 = 0.0294786177861719029113601772508066971031878720367673319179859403

 

0.8 and 0.2 how it is posible i can t understand i know tha one of them is Pin and the other Pout

 

sorry that i am asking proisaic questions i just wanna to understand

Solveit  Mar 29, 2016
 #6
avatar+33661 
0

nCr(400, 88)*0.8^312*0.2^88 = 0.0294786...   is the probability that exactly 88 of the sample of 400 were born outside the US; no more and no fewer.

 Mar 29, 2016
 #7
avatar+2498 
0

That is it i get it Thank you very much Alan !

Solveit  Mar 29, 2016

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