A theoretical justification based on a certain material fail

A theoretical justification based on a certain material failure mechanism underlies the assumption that ductile strength X of a material has a lognormal distribution. Suppose the parameters are = 4.8 and = 0.11.

(e) If ten different samples of an alloy steel of this type were subjected to a strength test, how many would you expect to have strength of at least 125? (Round your answer to three decimal places.)
samples

(f) If the smallest 5% of strength values were unacceptable, what would the minimum acceptable strength be? (Round your answer to three decimal places.)

Solution