SOLUTION: After calculating the sample size needed to estimate a population proportion to within .04, your statistics professor told you the maximum allowable error must be reduced to just .

Question 1089638: After calculating the sample size needed to estimate a population proportion to within .04, your statistics professor told you the maximum allowable error must be reduced to just .01. If the original calculation led t a sample size of 800, the sample size will now have to be:
I know the answer but do not know how to get it. Can someone please help me?!
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!

We will use the formula

as shown on this page (scroll down to the section titled "Finding n to Estimate a Proportion")

------------------------------

Initially we're told that an error of E = 0.04 will lead to a sample size of n = 800. We don't know z and we don't know p. We don't need to know p. If p is unknown, then we assume that p = 0.5. The goal here is to find z given n = 800 and E = 0.04. Let's do that

So the z critical value is roughly z = 2.2627

---------------------------------------

We'll use z = 2.2627 and the new error threshold of E = 0.01 to find n to be...

(round up to the nearest whole number)

The new sample size needed is approximately 12800

RELATED QUESTIONS
After calculating the sample size needed to estimate a population proportion to within... (answered by Boreal)

After calculating the sample size needed to estimate a population proportion to within... (answered by oscargut)

After you calculate the sample size needed to estimate a population proportion to within... (answered by robertb)

You want to estimate, with 95% confidence, the population proportion of U.S. adults who... (answered by stanbon)

you want to obtain a sample to estimate the population proportion you would like to be at (answered by ewatrrr)

A researcher wants to make a 95% confidence interval for the population proportion. A... (answered by stanbon)

You wish to estimate with 95% confidence the population proportion of US adults who think (answered by jim_thompson5910)

You want to obtain a sample to estimate a population proportion. You have no reasonable... (answered by Boreal)

Determine the sample size necessary to estimate a population proportion to within .03 (answered by stanbon)