A researcher wishes to estimate the proportion of adults who have high-speed Internet access. What size sample should be obtained if she wishes the estimate to be within 0.04 with 99% confidence if

(a) she uses a previous estimate of 0.52?

(b) she does not use any prior estimates?

Step-by-step explanation:

Solution:-

- The sample size = n

- The Error of estimation, E = 0.04

- The confidence level, CI = 99%

a)

What size sample should be obtained when she uses previous estimate of p = 0.52?

- We are given the sample proportion p = 0.52, the required sample size is a function of confidence value and error of estimation (E):

Where,

- The critical value of the confidence level = 99% would be:

           significance level ( α ) = 1 - CI = 1 - 0.99 = 0.01

           Z-critical = Z_α/2 = Z_0.005 = 2.575  

- The required sample size (n) can be calculated:

- Hence, the minimum required sample size (n) should be = 612 adults.  

b)

- If the preliminary estimate of proportion is missing or not given, we are to assume the proportion p = 0.5.

- Similarly, repeat the calculations for sample size (n) when p = 0.5

- Hence, the minimum required sample size (n) should be = 664 adults.  

geometry: triangles

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answers archive

call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584

answer: 819.89 miles across america

step-by-step explanation: