Question 880703
The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 175 and a variance of 16. The material is considered defective if the breaking strength is less than 165.8 pounds. What is the probability that a single, randomly selected piece of material will be defective?
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std = 16/2 = 8
z(165.8) = (168.5-175)/8 = -0.8125 
P(x < 165.8) = P(z< -0.8125) = 0.2083
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Cheers,
Stan H.