Hi
The average years of employee experience at a company with 10,000 employees is
normally distributed, with a standard deviation of 12 years.
If a sample of 50 employees indicates a mean age of 38,
calculate 90 percent confidence intervals for the population mean.
ME = 1.645[38/sqrt(50)] = 8.8402
CI:
99 percent confidence intervals for the population mean.
ME =2.575[38/sqrt(50)] = 13.8381
CI:
a a/2 crtical regions
90% 0.1 5% z <-1.645 z >+1.645
92% 0.8 4% z <-1.751 z >+1.751
95% 0.05 2.50% z <-1.96 z >+1.96
98% 0.02 1% z <-2.33 z >+2.33
99% 0.01 0.50% z<-2.575 z >+2.575