# statistics

the breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 125 and a variance of 25. The material is considered defective if the breaking strength is less than 113 pounds. What is the probability that a single, randomly selected piece of material will be defective?

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1. P(x < 113)

mean = 125
Standard deviation = sqrt(variance)
Standard deviation = 5

z = (113-125)/5
z = -12/5
z = -2.4
P ( z < -2.4) = 0.0082

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posted by Kuai

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