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 January 28th, 2019, 09:24 AM #1 Newbie   Joined: Jan 2019 From: California Posts: 3 Thanks: 0 Please help with math A researcher is studying a population of bats in which 16% of the population has a certain trait. The researcher wants sampling distribution with a standard deviation that is less than 2%. Which sample sizes could the researcher use? Select all that apply : n=200 n=300 n=400 n=500
 January 28th, 2019, 09:48 AM #2 Senior Member     Joined: Sep 2015 From: USA Posts: 2,549 Thanks: 1399 What they probably want you to do is note that $\sigma_p= \sqrt{p(1-p)}$ Then with a sample of size $n$ $\sigma = \dfrac{\sigma_p}{\sqrt{n}}$ i.e. $\sigma = \sqrt{\dfrac{p(1-p)}{n}}$ I'll let you put your number, $p=0.16$, in and solve for $n$ such that $\sigma < 0.02$ Thanks from topsquark and Horribleatmath
 January 30th, 2019, 10:10 AM #3 Newbie   Joined: Jan 2019 From: California Posts: 3 Thanks: 0 Can I please get the answer? I still don't get how. Last edited by skipjack; January 31st, 2019 at 02:33 AM.
January 30th, 2019, 10:21 AM   #4
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Quote:
 Originally Posted by Horribleatmath Can I please get the answer? I still don't get how.
He already told you.

Quote:
 Originally Posted by romsek What they probably want you to do is note that I'll let you put your number, $p=0.16$, in and solve for $n$ such that $\sigma < 0.02$
Do you have a more specific question than "what is the answer?" Can you solve this for n?

-Dan

Last edited by skipjack; January 31st, 2019 at 02:34 AM.

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