Question

Calculate the lower confidence limit (LCL) of the mean for the following: x¯= 400, n = 84, σ = 7 (sigma), α = 0.01 (alpha).

Answer 1

Solution :

Given that,

Sample size = n = 84

Z = 2.326

Margin of error = E = Z * ( /n)

= 2.326 * (7 / 84)

Margin of error = E = 1.78

The lower confidence interval estimate of the population mean is,

- E

400 - 1.78

398.22

LCL: 398.22