116. The article “Response of SiCf /Si3N4 Composites Under Static and Cyclic Loading—An Experimental and Statistical Analysis” (J. of Engr. Materials and Technology, 1997: 186–193) suggests that tensile strength (MPa) of composites under specified conditions can be modeled by a Weibull distribution with 
9 and

180.

a. Sketch a graph of the density function.

b. What is the probability that the strength of a randomly selected specimen will exceed 175? Will be between 150 and 175?

c. If two randomly selected specimens are chosen and their strengths are independent of one another, what is