Question

Which of the following is true about a 95 % confidence interval? Select all that are true

a)accounts for bias in the calculation of the mean

b)Provides a range within which we are 95% confident the population mean resides

c)95% of the population values lies within the confidence interval

d)if 20 samples of that sample size are taken its likely 19 of them contain the mean

Answer 1

solution

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 = 1.96 ( Using z table ( see the 0.025 value in standard normal (z) table corresponding z value is 1.96 )

the correct option is 95% of the population values lies within the confidence interval

confidence interval is always within the interval