GBS_221_chapter_8_student_data_files.xlsx - we know pop std dev we don't know pop std deviation sample mean z\u03b1\/2 excel function to calculate zscore

# GBS_221_chapter_8_student_data_files.xlsx - we know pop std...

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we know pop std dev we don't know pop std deviation sample mean excel function to calculate zscore =norm.s.inv standard normal distribution norm.s.inv at alpha over 2 z α/2 common confidence levels: level of significance 90% 10% 95% 5% 99% 1% level of significance is called the alpha value outside of range does not contain the true population or mean is equal to 1 minus the confidence level margin of error tells us how wide our interval needs to be in order to reach the designated level of confidence 8.2 Confidence Level when σ is known Formula for the Confidence Interval for the mean (σ known) std error of mean - from chp 7 margin of error known as α - alpha x α/ x x α/ x σ z x LCL σ z x UCL 2 2 n σ σ x x α/ x σ z ME 2  sample confidence level of sign alpha /2 finding z sc std error margin of e UCL LCL Statement n σ σ x x α/ x x α/ x σ z x LCL σ z x UCL 2 2 mean 247.8 std dev 39 n - sam siz 35 e interval 0.9 nificance 0.1 0.05 core @ a/2 1.644854 for margin of error always convert to positive 6.592203 error 10.84321 258.6432 236.9568 we are 90% confident that the mean luxury cosst of hotels in the US per night is between \$236.96 abd \$258. .64. norm.s.inv converts any sample mean to any sample normal distribution c. As the precision of estimates increase the margin of error increases sample mean 507 std dev 63 n - sam siz 30 confidence interval 0.9 level of significance 0.1 alpha /2 0.05 finding z score @ a/2 1.644854 for margin of error always convert to positive std error 11.50217 margin of error 18.91939 UCL 525.9194 LCL 488.0806 sample mean 507 std dev 63 n - sam siz 60 confidence interval 0.9 level of significance 0.1 alpha /2 0.05 finding z score @ a/2 1.644854 for margin of error always convert to positive std error 8.133265 margin of error 13.37803 UCL 520.378 LCL 493.622 population sample sample sample confidence level of sign zscore @ a std error margin of e UCL LCL we are 98% because 20 mean 20.3  • • • 