Z = (score -mean) /sd
z = (126.2-135)/4
z = -9.8/4 = -2.45
z-table
The breaking strength (in pounds) of a certain new synthetic is normally distributed, with a mean of 135 and a variance of 16. The material is considered defective if the breaking strength is less than 126.2 pounds. What is the probability that a single, randomly selected piece of material will be defective? (You may need to use the standard normal distribution table. Round your answer to four decimal places.)
1 answer