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January 28th, 2019, 09:24 AM   #1
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Unhappy 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
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January 28th, 2019, 09:48 AM   #2
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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
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January 30th, 2019, 10:10 AM   #3
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Can I please get the answer? I still don't get how.

Last edited by skipjack; January 31st, 2019 at 02:33 AM.
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January 30th, 2019, 10:21 AM   #4
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Quote:
Originally Posted by Horribleatmath View Post
Can I please get the answer? I still don't get how.
He already told you.

Quote:
Originally Posted by romsek View Post
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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