(12pts) Problem 1 Material strength investigations provide a rich area of application for statistical methods. The article "Effects of Aggregates and Microfillers on the Flexural Properties of Concrete" (Magazine of Concrete Research, 1997: 81-98) reported on a study of strength properties of high-performance concrete obtained by using superplasticizers and certain binders. The compressive strength of such concrete had previously been investigated, but not much was known about flexural strength (a measure of ability to resist failure in bending). The follow- ing data on flexural strength (in MegaPascal, MPa, where 1 Pa (Pascal) 5 1.45 3 1024 psi) appeared in the article cited: 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) Construct a stem-and-leaf display of the data, (b) Construct a frequency table and find the mean, the median and the mode. (c) Find the Ist, 2nd and 3rd quartiles. (d) Find the 85th percentile