An engineer selects 10 components at random and measures their strengths. It is reported that the average strength of the components is between 72.3 and 74.5 with 99% confidence.
(a) What is the sample standard deviation of the 10 component strengths?
(b) If a 99% two-sided confidence interval is desired with a length no longer than 1.0. about how many additional components would you recommend be tested?