The Accompanying Data Describe Flexural Strength (Mpa) for Concrete Beams

Multiple Choice

The accompanying data describe flexural strength (Mpa) for concrete beams of a certain type was introduced in Example 1.2. $$\begin{array} { l l l l l l l } 9.2 & 9.7 & 8.8 & 10.7 & 8.4 & 8.7 & 10.7 \\6.9 & 8.2 & 8.3 & 7.3 & 9.1 & 7.8 & 8.0 \\8.6 & 7.8 & 7.5 & 8.0 & 7.3 & 8.9 & 10.0 \\8.8 & 8.7 & 12.6 & 12.3 & 12.8 & 11.7 &\end{array}$$

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: $\sum x _ { i } = 246.8 .$
B) Calculate a point estimate of the strength value that separates 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 $\sigma$
Which estimator did you use? Hint: $\sum x _ { i } ^ { 2 } = 2327.54$
D) Calculate a point estimate of the proportion of all such beams whose flexural strength exceeds 11 Mpa. Hint: Think of an observation as a "success" if it exceeds 11.
E) Calculate a point estimate of the population coefficient of variation $\sigma / \mu$
And state which estimator you used.