The accompanying data on flexural strength (MPa) for con- crete beams of a certain type was introduced in Example 1.2. 5.9 7.2 7.3 6.3. 8.1 6.8 7.0 7.6 6.8 6.5 7.0 6.3 7.9 9.0 8.2 8.7 7.8 9.7 7.4 7.7 9.7 7.8 7.7 11.6 11.3 11.8 10.7

a. Calculate a point estimate of the mean value of strength for the conceptual population of all beams manufactured in this fashion, and state which estimator you used. [Hint: Ex = 219.8.]

b. Calculate a point estimate of the strength value that sepa- rates the weakest 50% of all such beams from the strongest 50%, and state which estimator you used.

c. Calculate and interpret a point estimate of the population standard deviation . Which estimator did you use? [Hint: 2x = 1860.94.]

d. Calculate a point estimate of the proportion of all such beams whose flexural strength exceeds 10 MPa. [Hint: Think of an observation as a "success" if it exceeds 10.]

e. Calculate a point estimate of the population coefficient of variation /u, and state which estimator you used.