We provide a sample mean, sample size, population standard deviation, and confidence level. In each case, perform the following tasks:

a. Use the one-mean z-interval procedure to find a confidence interval for the mean of the population from which the sample was drawn.

b. Obtain the margin of error by taking half the length of the confidence interval.

c. Obtain the margin of error by using Formula 8.1.

Formula 8.1

The margin of error for the estimate of μ is z_α/2 · σ/ √n, which is denoted by the letter E. Thus,

x̄ = 55, n = 16, σ = 5, confidence level = 99%

E = Z/2.0/n.