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Question

Find a sample size for a confidence interval, SD not known : 41% of Jacksonville residents said that they had been in a hurricane. How many adults should be surveyed to estimate the true proportion of adults who have been in a hurricane, with a 95% confidence interval 6% wide?

Answer

Figure out the following variables:

z a/2 = z-score(CI/2 .95 / 2 = .475) = z-score for .475 is 1.96

E (margin of error) = width/2 = 6% / 2 = .06 / 2 = .03

p = 41% = .41

q = 1-p = 1 - .41 = .59

Multiply p by q = .41 × .59 = .2419

Sample size = (z a/2 : E)^2 x (p x q)

z a/2 = z-score(CI/2 .95 / 2 = .475) = z-score for .475 is 1.96

E (margin of error) = width/2 = 6% / 2 = .06 / 2 = .03

p = 41% = .41

q = 1-p = 1 - .41 = .59

Multiply p by q = .41 × .59 = .2419

Sample size = (z a/2 : E)^2 x (p x q)

Question

Find a sample size for a confidence interval, SD not known : 41% of Jacksonville residents said that they had been in a hurricane. How many adults should be surveyed to estimate the true proportion of adults who have been in a hurricane, with a 95% confidence interval 6% wide?

Answer

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Question

Find a sample size for a confidence interval, SD not known : 41% of Jacksonville residents said that they had been in a hurricane. How many adults should be surveyed to estimate the true proportion of adults who have been in a hurricane, with a 95% confidence interval 6% wide?

Answer

Figure out the following variables:

z a/2 = z-score(CI/2 .95 / 2 = .475) = z-score for .475 is 1.96

E (margin of error) = width/2 = 6% / 2 = .06 / 2 = .03

p = 41% = .41

q = 1-p = 1 - .41 = .59

Multiply p by q = .41 × .59 = .2419

Sample size = (z a/2 : E)^2 x (p x q)

z a/2 = z-score(CI/2 .95 / 2 = .475) = z-score for .475 is 1.96

E (margin of error) = width/2 = 6% / 2 = .06 / 2 = .03

p = 41% = .41

q = 1-p = 1 - .41 = .59

Multiply p by q = .41 × .59 = .2419

Sample size = (z a/2 : E)^2 x (p x q)

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#### pdf

owner: naxplast06 - (no access) - Deviant S. - The Practically Cheating Statistics Handbook (2010, CreateSpace Independent Publishing Platform).pdf, p108

status | not learned | measured difficulty | 37% [default] | last interval [days] | |||
---|---|---|---|---|---|---|---|

repetition number in this series | 0 | memorised on | scheduled repetition | ||||

scheduled repetition interval | last repetition or drill |

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