A theoretical justification based on a certain material failure mechanism underlies the assumption that ductile strength of a material has a lognormal distribution. Suppose the values of the parameters are µ = 5 and σ = 0.1.

a. What proportion of material specimens have ductile strength exceeding 120? What proportion have a ductile strength of at least 120?

b. What proportion of material specimens have a ductile strength between 110 and 130?

c. If the smallest 5% of strength values were unacceptable. what would be the minimum acceptable strength?

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a Find the proportion of material specimens that have a ductile strength exceeding 120 Assum... View the full answer