In Exercise 8.31, you found a 95% confidence interval for the mean amount of all venture-capital investments

Question:

In Exercise 8.31, you found a 95% confidence interval for the mean amount of all venture-capital investments in the fiber optics business sector to be from $5.389 million to $7.274 million. Obtain the margin of error by
a. Taking half the length of the confidence interval.
b. Using the formula in Definition 8.3 on page 321. (Recall that n = 18 and σ = $2.04 million.)