8.87 Venture-Capital Investments. In Exercise 8.69, 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 mil- lion to $7.274 million. Obtain the margin of error by a. taking half the length of the confidence interval. b. using Formula 8.1 on page 342. (Recall that n = 18 and that o = $2.04 million.)