Question

What sample size is needed to give a margin of error within ±4% in estimating a population proportion with 95% confidence?

Use z-values rounded to three decimal places. Round your answer up to the nearest integer.

Sample size = ___________________

Answer #1

Solution:

Given that,

= 0.5

1 - = 1 - 0.5 = 0.5

margin of error = E = 4% = 0.04

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z_{/2}
= Z_{0.025} = 1.960

Sample size = n = ((Z_{
/ 2}) / E)^{2} *
* (1 -
)

= (1.960 / 0.04)^{2} * 0.5 * 0.5 = 600.25 = 601

n = sample size = 601

What sample size is needed to give a margin of error within
±1.5% in estimating a population proportion with 95%
confidence?
Round your answer up to the nearest integer.
Sample size =

What sample size is needed to give a margin of error within
±2.5% in estimating a population proportion with 99% confidence? An
initial small sample has p^=0.78.
Round the answer up to the nearest integer.

What sample size is needed to give a margin of error within
+-2.5 in estimating a population mean with 95% confidence, assuming
a previous sample had s=3.7
Round to nearest whole integer.

What sample size is needed to give a margin of error within
±2.5% in estimating a population proportion with 90%
confidence? We estimate that the population proportion is about
0.4

What Influences the Sample Size? We examine the effect of
different inputs on determining the sample size needed to obtain a
specific margin of error when finding a confidence interval for a
proportion.
Find the sample size needed to give, with 95% confidence, a
margin of error within ± 6% when estimating a proportion. Within ±
4% . Within ± 1% . (Assume no prior knowledge about the population
proportion p .) Round your answers up to the nearest integer....

What sample size is needed to give the desired margin of error
with margin of error= +/-5 with 95% confidence, s=18.
The answer is n is greater than or equal to 50 but i dont know
how to get there

What sample size is needed to give a margin of error of 5% with
a 95% confidence interval?
Sample size =

If you want to be 99% confident of estimating the population
proportion to within a sampling error of ± 0.05 and there is
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0.37, what sample size is needed?
A sample size of is needed.
(Round up to the nearest integer.)

Find the minimum sample size needed when estimating population
proportion with 98% confidence level, margin of error to be within
5% and
(a) if pˆ = .768 .
n =
(b) if pˆ is unknown.
n =

Chapter 6, Section 2-CI, Exercise 110
What Influences the Sample Size Needed?
In this exercise, we examine the effect of the margin of error on
determining the sample size needed.
Find the sample size needed to give a margin of error within ± 2
with 99% confidence. With 95% confidence. With 90% confidence.
Assume that we use ά =30 as out estimate of the standard deviation
in each case.
Round your answers up to the nearest integer.
99% n= _______...

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