If you want to be 95​% confident of estimating the population proportion to within a sampling error of plus or minus0.05 and there is historical evidence that the population proportion is approximately 0.37​, what sample size is​ needed? A sample size of nothing is needed. ​(Round up to the nearest​ integer.)

Respuesta :

Answer: 359

Step-by-step explanation:

When prior estimate of population proportion is given , then the formula we use to find the sample size is given by :-

[tex]n=p(1-p)(\dfrac{z^*}{E})^2[/tex]

, where p=  prior estimate of population proportion

z*= critical-value.

E= Margin of sampling error.

As per given , we have

p=0.37

E= ± 0.05

We know that critical z-value corresponding to 95% confidence level = z*=1.960  [Using z-table]

Then, Required sample size  :

[tex]n=(0.37)(1-0.37)(\dfrac{(1.96)}{0.05})^2[/tex]

[tex]\Rightarrow\ n=(0.37)(0.63)(39.2)^2[/tex]

[tex]\Rightarrow\ n=0.2331\times1536.64\\\\\Rightarrow\ n=358.190784\approx359[/tex] [Rounded to next integer.]

Hence, the required minimum sample size = 359